diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index 0a19c690fc6a5..0bbba217b2fd0 100644
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -1904,8 +1904,6 @@ ORIGIN: ../../../flutter/lib/ui/window/pointer_data_packet_converter.cc + ../../
 ORIGIN: ../../../flutter/lib/ui/window/pointer_data_packet_converter.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/ui/window/viewport_metrics.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/ui/window/viewport_metrics.h + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/lib/ui/window/window.cc + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/lib/ui/window/window.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/annotations.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/canvas.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/channel_buffers.dart + ../../../flutter/LICENSE
@@ -4634,8 +4632,6 @@ FILE: ../../../flutter/lib/ui/window/pointer_data_packet_converter.cc
 FILE: ../../../flutter/lib/ui/window/pointer_data_packet_converter.h
 FILE: ../../../flutter/lib/ui/window/viewport_metrics.cc
 FILE: ../../../flutter/lib/ui/window/viewport_metrics.h
-FILE: ../../../flutter/lib/ui/window/window.cc
-FILE: ../../../flutter/lib/ui/window/window.h
 FILE: ../../../flutter/lib/web_ui/lib/annotations.dart
 FILE: ../../../flutter/lib/web_ui/lib/canvas.dart
 FILE: ../../../flutter/lib/web_ui/lib/channel_buffers.dart
diff --git a/common/constants.h b/common/constants.h
index 378f7c84e7c0f..668aa4f64ebd2 100644
--- a/common/constants.h
+++ b/common/constants.h
@@ -7,6 +7,32 @@
 
 namespace flutter {
 constexpr double kMegaByteSizeInBytes = (1 << 20);
+
+// The ID for the implicit view if the implicit view is enabled.
+//
+// The implicit view is a compatibility mechanism to help the transition from
+// the older single-view APIs to the newer multi-view APIs. The two sets of APIs
+// use different models for view management. The implicit view mechanism allows
+// single-view APIs to operate a special view as if other views don't exist.
+//
+// In the regular multi-view model, all views should be created by
+// `Shell::AddView` before being used, and removed by `Shell::RemoveView` to
+// signify that they are gone. If a view is added or removed, the framework
+// (`PlatformDispatcher`) will be notified. New view IDs are always unique,
+// never reused. Operating a non-existing view is an error.
+//
+// The implicit view is another special view in addition to the "regular views"
+// as above. The shell starts up having the implicit view, which has a fixed
+// view ID of `kFlutterImplicitViewId` and is available throughout the lifetime
+// of the shell. `Shell::AddView` or `RemoveView` must not be called for this
+// view. Even when the window that shows the view is closed, the framework is
+// unaware and might continue rendering into or operating this view.
+//
+// The single-view APIs, which are APIs that do not specify view IDs, operate
+// the implicit view. The multi-view APIs can operate all views, including the
+// implicit view if the target ID is `kFlutterImplicitViewId`, unless specified
+// otherwise.
+constexpr int64_t kFlutterImplicitViewId = 0;
 }  // namespace flutter
 
 #endif  // FLUTTER_COMMON_CONSTANTS_H_
diff --git a/lib/ui/BUILD.gn b/lib/ui/BUILD.gn
index 596dac782b3d4..8ad0197bb1d8d 100644
--- a/lib/ui/BUILD.gn
+++ b/lib/ui/BUILD.gn
@@ -155,8 +155,6 @@ source_set("ui") {
     "window/pointer_data_packet_converter.h",
     "window/viewport_metrics.cc",
     "window/viewport_metrics.h",
-    "window/window.cc",
-    "window/window.h",
   ]
 
   public_configs = [ "//flutter:config" ]
diff --git a/lib/ui/compositing/scene.cc b/lib/ui/compositing/scene.cc
index 17d00ea794c2a..5e44f3fcc27bf 100644
--- a/lib/ui/compositing/scene.cc
+++ b/lib/ui/compositing/scene.cc
@@ -10,7 +10,6 @@
 #include "flutter/lib/ui/painting/picture.h"
 #include "flutter/lib/ui/ui_dart_state.h"
 #include "flutter/lib/ui/window/platform_configuration.h"
-#include "flutter/lib/ui/window/window.h"
 #if IMPELLER_SUPPORTS_RENDERING
 #include "flutter/lib/ui/painting/display_list_deferred_image_gpu_impeller.h"
 #endif  // IMPELLER_SUPPORTS_RENDERING
diff --git a/lib/ui/dart_ui.cc b/lib/ui/dart_ui.cc
index b2fdbf88d4fc4..02a6b79978241 100644
--- a/lib/ui/dart_ui.cc
+++ b/lib/ui/dart_ui.cc
@@ -7,6 +7,7 @@
 #include <mutex>
 #include <string_view>
 
+#include "flutter/common/constants.h"
 #include "flutter/common/settings.h"
 #include "flutter/fml/build_config.h"
 #include "flutter/lib/ui/compositing/scene.h"
@@ -95,7 +96,6 @@ typedef CanvasPath Path;
   V(IsolateNameServerNatives::RemovePortNameMapping, 1)               \
   V(NativeStringAttribute::initLocaleStringAttribute, 4)              \
   V(NativeStringAttribute::initSpellOutStringAttribute, 3)            \
-  V(PlatformConfigurationNativeApi::ImplicitViewEnabled, 0)           \
   V(PlatformConfigurationNativeApi::DefaultRouteName, 0)              \
   V(PlatformConfigurationNativeApi::ScheduleFrame, 0)                 \
   V(PlatformConfigurationNativeApi::Render, 1)                        \
@@ -373,6 +373,12 @@ void DartUI::InitForIsolate(const Settings& settings) {
       Dart_PropagateError(result);
     }
   }
+
+  result = Dart_SetField(dart_ui, ToDart("_implicitViewId"),
+                         Dart_NewInteger(kFlutterImplicitViewId));
+  if (Dart_IsError(result)) {
+    Dart_PropagateError(result);
+  }
 }
 
 }  // namespace flutter
diff --git a/lib/ui/hooks.dart b/lib/ui/hooks.dart
index 7d31bd4f0c2f1..5c2244d43a9ad 100644
--- a/lib/ui/hooks.dart
+++ b/lib/ui/hooks.dart
@@ -4,6 +4,60 @@
 
 part of dart.ui;
 
+@pragma('vm:entry-point')
+void _addView(
+  int viewId,
+  double devicePixelRatio,
+  double width,
+  double height,
+  double viewPaddingTop,
+  double viewPaddingRight,
+  double viewPaddingBottom,
+  double viewPaddingLeft,
+  double viewInsetTop,
+  double viewInsetRight,
+  double viewInsetBottom,
+  double viewInsetLeft,
+  double systemGestureInsetTop,
+  double systemGestureInsetRight,
+  double systemGestureInsetBottom,
+  double systemGestureInsetLeft,
+  double physicalTouchSlop,
+  List<double> displayFeaturesBounds,
+  List<int> displayFeaturesType,
+  List<int> displayFeaturesState,
+  int displayId,
+) {
+  final _ViewConfiguration viewConfiguration = _buildViewConfiguration(
+    devicePixelRatio,
+    width,
+    height,
+    viewPaddingTop,
+    viewPaddingRight,
+    viewPaddingBottom,
+    viewPaddingLeft,
+    viewInsetTop,
+    viewInsetRight,
+    viewInsetBottom,
+    viewInsetLeft,
+    systemGestureInsetTop,
+    systemGestureInsetRight,
+    systemGestureInsetBottom,
+    systemGestureInsetLeft,
+    physicalTouchSlop,
+    displayFeaturesBounds,
+    displayFeaturesType,
+    displayFeaturesState,
+    displayId,
+  );
+  PlatformDispatcher.instance._addView(viewId, viewConfiguration);
+}
+
+@pragma('vm:entry-point')
+void _removeView(int viewId) {
+  PlatformDispatcher.instance._removeView(viewId);
+}
+
 @pragma('vm:entry-point')
 void _updateDisplays(
   List<int> ids,
diff --git a/lib/ui/natives.dart b/lib/ui/natives.dart
index 44ab3e6092e0f..72a55ab8b7d57 100644
--- a/lib/ui/natives.dart
+++ b/lib/ui/natives.dart
@@ -112,3 +112,12 @@ _ScheduleImmediateClosure _getScheduleMicrotaskClosure() => _scheduleMicrotask;
 // rendering.
 @pragma('vm:entry-point')
 bool _impellerEnabled = false;
+
+// Used internally to indicate whether the embedder enables the implicit view,
+// and the implicit view's ID if so.
+//
+// The exact value of this variable is an implementation detail that may change
+// at any time. Apps should always use PlatformDispatcher.implicitView to
+// determine the current implicit view, if any.
+@pragma('vm:entry-point')
+int? _implicitViewId;
diff --git a/lib/ui/painting/canvas.cc b/lib/ui/painting/canvas.cc
index 403a4c3f440a1..0b090b68c9a7b 100644
--- a/lib/ui/painting/canvas.cc
+++ b/lib/ui/painting/canvas.cc
@@ -13,7 +13,6 @@
 #include "flutter/lib/ui/painting/paint.h"
 #include "flutter/lib/ui/ui_dart_state.h"
 #include "flutter/lib/ui/window/platform_configuration.h"
-#include "flutter/lib/ui/window/window.h"
 
 using tonic::ToDart;
 
@@ -621,11 +620,16 @@ void Canvas::drawShadow(const CanvasPath* path,
   }
 
   // Not using SafeNarrow because DPR will always be a relatively small number.
-  SkScalar dpr = static_cast<float>(UIDartState::Current()
-                                        ->platform_configuration()
-                                        ->get_window(0)
-                                        ->viewport_metrics()
-                                        .device_pixel_ratio);
+  const ViewportMetrics* metrics =
+      UIDartState::Current()->platform_configuration()->GetMetrics(0);
+  SkScalar dpr;
+  // TODO(dkwingsmt): We should support rendering shadows on non-implicit views.
+  // However, currently this method has no way to get the target view ID.
+  if (metrics == nullptr) {
+    dpr = 1.0f;
+  } else {
+    dpr = static_cast<float>(metrics->device_pixel_ratio);
+  }
   if (display_list_builder_) {
     // The DrawShadow mechanism results in non-public operations to be
     // performed on the canvas involving an SkDrawShadowRec. Since we
diff --git a/lib/ui/platform_dispatcher.dart b/lib/ui/platform_dispatcher.dart
index a8ff3144b6a28..c8ebb246ae548 100644
--- a/lib/ui/platform_dispatcher.dart
+++ b/lib/ui/platform_dispatcher.dart
@@ -66,14 +66,6 @@ typedef ErrorCallback = bool Function(Object exception, StackTrace stackTrace);
 // A gesture setting value that indicates it has not been set by the engine.
 const double _kUnsetGestureSetting = -1.0;
 
-// The view ID of PlatformDispatcher.implicitView. This is an
-// implementation detail that may change at any time. Apps
-// should always use PlatformDispatcher.implicitView to determine
-// the current implicit view, if any.
-//
-// Keep this in sync with kImplicitViewId in window/platform_configuration.cc.
-const int _kImplicitViewId = 0;
-
 // A message channel to receive KeyData from the platform.
 //
 // See embedder.cc::kFlutterKeyDataChannel for more information.
@@ -218,10 +210,29 @@ class PlatformDispatcher {
   /// * [View.of], for accessing the current view.
   /// * [PlatformDispatcher.views] for a list of all [FlutterView]s provided
   ///   by the platform.
-  FlutterView? get implicitView => _implicitViewEnabled() ? _views[_kImplicitViewId] : null;
-
-  @Native<Handle Function()>(symbol: 'PlatformConfigurationNativeApi::ImplicitViewEnabled')
-  external static bool _implicitViewEnabled();
+  FlutterView? get implicitView {
+    final FlutterView? result = _views[_implicitViewId];
+    // Make sure [implicitView] agrees with `_implicitViewId`.
+    assert((result != null) == (_implicitViewId != null),
+      (_implicitViewId != null) ?
+        'The implicit view ID is $_implicitViewId, but the implicit view does not exist.' :
+        'The implicit view ID is null, but the implicit view exists.');
+    // Make sure [implicitView] never chages.
+    assert(() {
+      if (_debugRecordedLastImplicitView) {
+        assert(identical(_debugLastImplicitView, result),
+          'The implicitView has changed:\n'
+          'Last: $_debugLastImplicitView\nCurrent: $result');
+      } else {
+        _debugLastImplicitView = result;
+        _debugRecordedLastImplicitView = true;
+      }
+      return true;
+    }());
+    return result;
+  }
+  FlutterView? _debugLastImplicitView;
+  bool _debugRecordedLastImplicitView = false;
 
   /// A callback that is invoked whenever the [ViewConfiguration] of any of the
   /// [views] changes.
@@ -249,6 +260,34 @@ class PlatformDispatcher {
     _onMetricsChangedZone = Zone.current;
   }
 
+  // Called from the engine, via hooks.dart
+  //
+  // Adds a new view with the specific view configuration.
+  //
+  // The implicit view must be added before [implicitView] is first called,
+  // which is typically the main function.
+  void _addView(int id, _ViewConfiguration viewConfiguration) {
+    assert(!_views.containsKey(id), 'View ID $id already exists.');
+    _views[id] = FlutterView._(id, this, viewConfiguration);
+    _invoke(onMetricsChanged, _onMetricsChangedZone);
+  }
+
+  // Called from the engine, via hooks.dart
+  //
+  // Removes the specific view.
+  //
+  // The target view must must exist. The implicit view must not be removed,
+  // or an assertion will be triggered.
+  void _removeView(int id) {
+    assert(id != _implicitViewId, 'The implicit view #$id can not be removed.');
+    if (id == _implicitViewId) {
+      return;
+    }
+    assert(_views.containsKey(id), 'View ID $id does not exist.');
+    _views.remove(id);
+    _invoke(onMetricsChanged, _onMetricsChangedZone);
+  }
+
   // Called from the engine, via hooks.dart.
   //
   // Updates the available displays.
@@ -264,15 +303,8 @@ class PlatformDispatcher {
   //
   // Updates the metrics of the window with the given id.
   void _updateWindowMetrics(int viewId, _ViewConfiguration viewConfiguration) {
-    final FlutterView? view = _views[viewId];
-    if (viewId == _kImplicitViewId && view == null) {
-      // TODO(goderbauer): Remove the implicit creation of the implicit view
-      //   when we have an addView API and the implicit view is added via that.
-      _views[viewId] = FlutterView._(viewId, this, viewConfiguration);
-    } else {
-      assert(view != null);
-      view!._viewConfiguration = viewConfiguration;
-    }
+    assert(_views.containsKey(viewId), 'View $viewId does not exist.');
+    _views[viewId]!._viewConfiguration = viewConfiguration;
     _invoke(onMetricsChanged, _onMetricsChangedZone);
   }
 
diff --git a/lib/ui/ui_dart_state.cc b/lib/ui/ui_dart_state.cc
index e66059fc515b3..4af7f0837d81e 100644
--- a/lib/ui/ui_dart_state.cc
+++ b/lib/ui/ui_dart_state.cc
@@ -9,6 +9,7 @@
 
 #include "flutter/fml/message_loop.h"
 #include "flutter/lib/ui/window/platform_configuration.h"
+#include "flutter/lib/ui/window/platform_message.h"
 #include "third_party/tonic/converter/dart_converter.h"
 #include "third_party/tonic/dart_message_handler.h"
 
diff --git a/lib/ui/window.dart b/lib/ui/window.dart
index fb0a65e800963..d86781ef2567f 100644
--- a/lib/ui/window.dart
+++ b/lib/ui/window.dart
@@ -406,7 +406,11 @@ class SingletonFlutterWindow extends FlutterView {
     'This feature was deprecated after v3.7.0-32.0.pre.'
   )
   SingletonFlutterWindow._() : super._(
-    _kImplicitViewId,
+    // TODO(dkwingsmt): This crashes if the implicit view is disabled. We need
+    // to resolve this by the time embedders are allowed to disable the implicit
+    // view.
+    // https://github.com/flutter/flutter/issues/131651
+    _implicitViewId!,
     PlatformDispatcher.instance,
     const _ViewConfiguration(),
   );
diff --git a/lib/ui/window/platform_configuration.cc b/lib/ui/window/platform_configuration.cc
index 8d11b747fd53b..c796bdfac5ef4 100644
--- a/lib/ui/window/platform_configuration.cc
+++ b/lib/ui/window/platform_configuration.cc
@@ -6,12 +6,13 @@
 
 #include <cstring>
 
+#include "flutter/common/constants.h"
 #include "flutter/lib/ui/compositing/scene.h"
 #include "flutter/lib/ui/ui_dart_state.h"
+#include "flutter/lib/ui/window/platform_message.h"
 #include "flutter/lib/ui/window/platform_message_response_dart.h"
 #include "flutter/lib/ui/window/platform_message_response_dart_port.h"
 #include "flutter/lib/ui/window/viewport_metrics.h"
-#include "flutter/lib/ui/window/window.h"
 #include "third_party/tonic/converter/dart_converter.h"
 #include "third_party/tonic/dart_args.h"
 #include "third_party/tonic/dart_library_natives.h"
@@ -22,9 +23,6 @@
 namespace flutter {
 namespace {
 
-// Keep this in sync with _kImplicitViewId in ../platform_dispatcher.dart.
-constexpr int kImplicitViewId = 0;
-
 Dart_Handle ToByteData(const fml::Mapping& buffer) {
   return tonic::DartByteData::Create(buffer.GetMapping(), buffer.GetSize());
 }
@@ -44,6 +42,13 @@ void PlatformConfiguration::DidCreateIsolate() {
 
   on_error_.Set(tonic::DartState::Current(),
                 Dart_GetField(library, tonic::ToDart("_onError")));
+  add_view_.Set(tonic::DartState::Current(),
+                Dart_GetField(library, tonic::ToDart("_addView")));
+  remove_view_.Set(tonic::DartState::Current(),
+                   Dart_GetField(library, tonic::ToDart("_removeView")));
+  update_window_metrics_.Set(
+      tonic::DartState::Current(),
+      Dart_GetField(library, tonic::ToDart("_updateWindowMetrics")));
   update_displays_.Set(
       tonic::DartState::Current(),
       Dart_GetField(library, tonic::ToDart("_updateDisplays")));
@@ -76,13 +81,110 @@ void PlatformConfiguration::DidCreateIsolate() {
                   Dart_GetField(library, tonic::ToDart("_drawFrame")));
   report_timings_.Set(tonic::DartState::Current(),
                       Dart_GetField(library, tonic::ToDart("_reportTimings")));
+}
 
-  // TODO(loicsharma): This should only be created if the embedder enables the
-  // implicit view.
-  // See: https://github.com/flutter/flutter/issues/120306
-  windows_.emplace(kImplicitViewId,
-                   std::make_unique<Window>(
-                       kImplicitViewId, ViewportMetrics{1.0, 0.0, 0.0, -1, 0}));
+void PlatformConfiguration::AddView(int64_t view_id,
+                                    const ViewportMetrics& view_metrics) {
+  auto [view_iterator, insertion_happened] =
+      metrics_.emplace(view_id, view_metrics);
+  FML_DCHECK(insertion_happened);
+
+  std::shared_ptr<tonic::DartState> dart_state = add_view_.dart_state().lock();
+  if (!dart_state) {
+    return;
+  }
+  tonic::DartState::Scope scope(dart_state);
+  tonic::CheckAndHandleError(tonic::DartInvoke(
+      add_view_.Get(),
+      {
+          tonic::ToDart(view_id),
+          tonic::ToDart(view_metrics.device_pixel_ratio),
+          tonic::ToDart(view_metrics.physical_width),
+          tonic::ToDart(view_metrics.physical_height),
+          tonic::ToDart(view_metrics.physical_padding_top),
+          tonic::ToDart(view_metrics.physical_padding_right),
+          tonic::ToDart(view_metrics.physical_padding_bottom),
+          tonic::ToDart(view_metrics.physical_padding_left),
+          tonic::ToDart(view_metrics.physical_view_inset_top),
+          tonic::ToDart(view_metrics.physical_view_inset_right),
+          tonic::ToDart(view_metrics.physical_view_inset_bottom),
+          tonic::ToDart(view_metrics.physical_view_inset_left),
+          tonic::ToDart(view_metrics.physical_system_gesture_inset_top),
+          tonic::ToDart(view_metrics.physical_system_gesture_inset_right),
+          tonic::ToDart(view_metrics.physical_system_gesture_inset_bottom),
+          tonic::ToDart(view_metrics.physical_system_gesture_inset_left),
+          tonic::ToDart(view_metrics.physical_touch_slop),
+          tonic::ToDart(view_metrics.physical_display_features_bounds),
+          tonic::ToDart(view_metrics.physical_display_features_type),
+          tonic::ToDart(view_metrics.physical_display_features_state),
+          tonic::ToDart(view_metrics.display_id),
+      }));
+}
+
+void PlatformConfiguration::RemoveView(int64_t view_id) {
+  if (view_id == kFlutterImplicitViewId) {
+    FML_LOG(ERROR) << "The implicit view #" << view_id << " cannot be removed.";
+    FML_DCHECK(false);
+    return;
+  }
+  size_t erased_elements = metrics_.erase(view_id);
+  FML_DCHECK(erased_elements != 0) << "View #" << view_id << " doesn't exist.";
+  (void)erased_elements;  // Suppress unused variable warning
+
+  std::shared_ptr<tonic::DartState> dart_state =
+      remove_view_.dart_state().lock();
+  if (!dart_state) {
+    return;
+  }
+  tonic::DartState::Scope scope(dart_state);
+  tonic::CheckAndHandleError(
+      tonic::DartInvoke(remove_view_.Get(), {
+                                                tonic::ToDart(view_id),
+                                            }));
+}
+
+bool PlatformConfiguration::UpdateViewMetrics(
+    int64_t view_id,
+    const ViewportMetrics& view_metrics) {
+  auto found_iter = metrics_.find(view_id);
+  if (found_iter == metrics_.end()) {
+    return false;
+  }
+
+  found_iter->second = view_metrics;
+
+  std::shared_ptr<tonic::DartState> dart_state =
+      update_window_metrics_.dart_state().lock();
+  if (!dart_state) {
+    return false;
+  }
+  tonic::DartState::Scope scope(dart_state);
+  tonic::CheckAndHandleError(tonic::DartInvoke(
+      update_window_metrics_.Get(),
+      {
+          tonic::ToDart(view_id),
+          tonic::ToDart(view_metrics.device_pixel_ratio),
+          tonic::ToDart(view_metrics.physical_width),
+          tonic::ToDart(view_metrics.physical_height),
+          tonic::ToDart(view_metrics.physical_padding_top),
+          tonic::ToDart(view_metrics.physical_padding_right),
+          tonic::ToDart(view_metrics.physical_padding_bottom),
+          tonic::ToDart(view_metrics.physical_padding_left),
+          tonic::ToDart(view_metrics.physical_view_inset_top),
+          tonic::ToDart(view_metrics.physical_view_inset_right),
+          tonic::ToDart(view_metrics.physical_view_inset_bottom),
+          tonic::ToDart(view_metrics.physical_view_inset_left),
+          tonic::ToDart(view_metrics.physical_system_gesture_inset_top),
+          tonic::ToDart(view_metrics.physical_system_gesture_inset_right),
+          tonic::ToDart(view_metrics.physical_system_gesture_inset_bottom),
+          tonic::ToDart(view_metrics.physical_system_gesture_inset_left),
+          tonic::ToDart(view_metrics.physical_touch_slop),
+          tonic::ToDart(view_metrics.physical_display_features_bounds),
+          tonic::ToDart(view_metrics.physical_display_features_type),
+          tonic::ToDart(view_metrics.physical_display_features_state),
+          tonic::ToDart(view_metrics.display_id),
+      }));
+  return true;
 }
 
 void PlatformConfiguration::UpdateDisplays(
@@ -309,10 +411,10 @@ void PlatformConfiguration::ReportTimings(std::vector<int64_t> timings) {
                                                }));
 }
 
-Window* PlatformConfiguration::get_window(int window_id) {
-  auto found = windows_.find(window_id);
-  if (found != windows_.end()) {
-    return found->second.get();
+const ViewportMetrics* PlatformConfiguration::GetMetrics(int view_id) {
+  auto found = metrics_.find(view_id);
+  if (found != metrics_.end()) {
+    return &found->second;
   } else {
     return nullptr;
   }
@@ -502,16 +604,6 @@ Dart_Handle PlatformConfigurationNativeApi::ComputePlatformResolvedLocale(
   return tonic::DartConverter<std::vector<std::string>>::ToDart(results);
 }
 
-Dart_Handle PlatformConfigurationNativeApi::ImplicitViewEnabled() {
-  UIDartState::ThrowIfUIOperationsProhibited();
-  bool enabled = UIDartState::Current()
-                     ->platform_configuration()
-                     ->client()
-                     ->ImplicitViewEnabled();
-
-  return Dart_NewBoolean(enabled);
-}
-
 std::string PlatformConfigurationNativeApi::DefaultRouteName() {
   UIDartState::ThrowIfUIOperationsProhibited();
   return UIDartState::Current()
diff --git a/lib/ui/window/platform_configuration.h b/lib/ui/window/platform_configuration.h
index 9226b457d07e8..90000890dde9f 100644
--- a/lib/ui/window/platform_configuration.h
+++ b/lib/ui/window/platform_configuration.h
@@ -14,9 +14,9 @@
 #include "flutter/assets/asset_manager.h"
 #include "flutter/fml/time/time_point.h"
 #include "flutter/lib/ui/semantics/semantics_update.h"
+#include "flutter/lib/ui/window/platform_message_response.h"
 #include "flutter/lib/ui/window/pointer_data_packet.h"
 #include "flutter/lib/ui/window/viewport_metrics.h"
-#include "flutter/lib/ui/window/window.h"
 #include "flutter/shell/common/display.h"
 #include "third_party/tonic/dart_persistent_value.h"
 #include "third_party/tonic/typed_data/dart_byte_data.h"
@@ -50,16 +50,6 @@ enum class AccessibilityFeatureFlag : int32_t {
 ///
 class PlatformConfigurationClient {
  public:
-  //--------------------------------------------------------------------------
-  /// @brief      Whether the platform provides an implicit view. If true,
-  ///             the Framework may assume that it can always render into
-  ///             the view with ID 0.
-  ///
-  ///             This value must not change for the lifetime of the
-  ///             application.
-  ///
-  virtual bool ImplicitViewEnabled() = 0;
-
   //--------------------------------------------------------------------------
   /// @brief      The route or path that the embedder requested when the
   ///             application was launched.
@@ -268,6 +258,42 @@ class PlatformConfiguration final {
   ///
   void DidCreateIsolate();
 
+  //----------------------------------------------------------------------------
+  /// @brief      Notify the framework that a new view is available.
+  ///
+  ///             A view must be added before other methods can refer to it,
+  ///             including the implicit view. Adding a view that already exists
+  ///             triggers an assertion.
+  ///
+  /// @param[in]  view_id           The ID of the new view.
+  /// @param[in]  viewport_metrics  The initial viewport metrics for the view.
+  ///
+  void AddView(int64_t view_id, const ViewportMetrics& view_metrics);
+
+  //----------------------------------------------------------------------------
+  /// @brief      Notify the framework that a view is no longer available.
+  ///
+  ///             Removing a view that does not exist triggers an assertion.
+  ///
+  ///             The implicit view (kFlutterImplicitViewId) should never be
+  ///             removed. Doing so triggers an assertion.
+  ///
+  /// @param[in]  view_id  The ID of the view.
+  ///
+  void RemoveView(int64_t view_id);
+
+  //----------------------------------------------------------------------------
+  /// @brief      Update the view metrics for the specified view.
+  ///
+  ///             If the view is not found, silently return false.
+  ///
+  /// @param[in]  view_id  The ID of the view.
+  /// @param[in]  metrics  The new metrics of the view.
+  ///
+  /// @return     Whether the view is found.
+  ///
+  bool UpdateViewMetrics(int64_t view_id, const ViewportMetrics& metrics);
+
   //----------------------------------------------------------------------------
   /// @brief      Update the specified display data in the framework.
   ///
@@ -416,7 +442,7 @@ class PlatformConfiguration final {
   /// @return     a pointer to the Window. Returns nullptr if the ID is not
   ///             found.
   ///
-  Window* get_window(int window_id);
+  const ViewportMetrics* GetMetrics(int view_id);
 
   //----------------------------------------------------------------------------
   /// @brief      Responds to a previous platform message to the engine from the
@@ -443,6 +469,9 @@ class PlatformConfiguration final {
  private:
   PlatformConfigurationClient* client_;
   tonic::DartPersistentValue on_error_;
+  tonic::DartPersistentValue add_view_;
+  tonic::DartPersistentValue remove_view_;
+  tonic::DartPersistentValue update_window_metrics_;
   tonic::DartPersistentValue update_displays_;
   tonic::DartPersistentValue update_locales_;
   tonic::DartPersistentValue update_user_settings_data_;
@@ -456,7 +485,8 @@ class PlatformConfiguration final {
   tonic::DartPersistentValue draw_frame_;
   tonic::DartPersistentValue report_timings_;
 
-  std::unordered_map<int64_t, std::unique_ptr<Window>> windows_;
+  // All current views' view metrics mapped from view IDs.
+  std::unordered_map<int64_t, ViewportMetrics> metrics_;
 
   // ID starts at 1 because an ID of 0 indicates that no response is expected.
   int next_response_id_ = 1;
@@ -490,8 +520,6 @@ class PlatformMessageHandlerStorage {
 //----------------------------------------------------------------------------
 class PlatformConfigurationNativeApi {
  public:
-  static Dart_Handle ImplicitViewEnabled();
-
   static std::string DefaultRouteName();
 
   static void ScheduleFrame();
diff --git a/lib/ui/window/platform_configuration_unittests.cc b/lib/ui/window/platform_configuration_unittests.cc
index 017055a41d91e..7410caeb66d6c 100644
--- a/lib/ui/window/platform_configuration_unittests.cc
+++ b/lib/ui/window/platform_configuration_unittests.cc
@@ -24,21 +24,17 @@ class PlatformConfigurationTest : public ShellTest {};
 TEST_F(PlatformConfigurationTest, Initialization) {
   auto message_latch = std::make_shared<fml::AutoResetWaitableEvent>();
 
-  auto nativeValidateConfiguration = [message_latch](
-                                         Dart_NativeArguments args) {
-    PlatformConfiguration* configuration =
-        UIDartState::Current()->platform_configuration();
-    ASSERT_NE(configuration->get_window(0), nullptr);
-    ASSERT_EQ(
-        configuration->get_window(0)->viewport_metrics().device_pixel_ratio,
-        1.0);
-    ASSERT_EQ(configuration->get_window(0)->viewport_metrics().physical_width,
-              0.0);
-    ASSERT_EQ(configuration->get_window(0)->viewport_metrics().physical_height,
-              0.0);
+  auto nativeValidateConfiguration =
+      [message_latch](Dart_NativeArguments args) {
+        PlatformConfiguration* configuration =
+            UIDartState::Current()->platform_configuration();
+        ASSERT_NE(configuration->GetMetrics(0), nullptr);
+        ASSERT_EQ(configuration->GetMetrics(0)->device_pixel_ratio, 1.0);
+        ASSERT_EQ(configuration->GetMetrics(0)->physical_width, 0.0);
+        ASSERT_EQ(configuration->GetMetrics(0)->physical_height, 0.0);
 
-    message_latch->Signal();
-  };
+        message_latch->Signal();
+      };
 
   Settings settings = CreateSettingsForFixture();
   TaskRunners task_runners("test",                  // label
@@ -68,27 +64,22 @@ TEST_F(PlatformConfigurationTest, Initialization) {
 TEST_F(PlatformConfigurationTest, WindowMetricsUpdate) {
   auto message_latch = std::make_shared<fml::AutoResetWaitableEvent>();
 
-  auto nativeValidateConfiguration = [message_latch](
-                                         Dart_NativeArguments args) {
-    PlatformConfiguration* configuration =
-        UIDartState::Current()->platform_configuration();
-
-    ASSERT_NE(configuration->get_window(0), nullptr);
-    configuration->get_window(0)->UpdateWindowMetrics(
-        ViewportMetrics{2.0, 10.0, 20.0, 22, 0});
-    ASSERT_EQ(
-        configuration->get_window(0)->viewport_metrics().device_pixel_ratio,
-        2.0);
-    ASSERT_EQ(configuration->get_window(0)->viewport_metrics().physical_width,
-              10.0);
-    ASSERT_EQ(configuration->get_window(0)->viewport_metrics().physical_height,
-              20.0);
-    ASSERT_EQ(
-        configuration->get_window(0)->viewport_metrics().physical_touch_slop,
-        22);
+  auto nativeValidateConfiguration =
+      [message_latch](Dart_NativeArguments args) {
+        PlatformConfiguration* configuration =
+            UIDartState::Current()->platform_configuration();
 
-    message_latch->Signal();
-  };
+        ASSERT_NE(configuration->GetMetrics(0), nullptr);
+        bool has_view = configuration->UpdateViewMetrics(
+            0, ViewportMetrics{2.0, 10.0, 20.0, 22, 0});
+        ASSERT_TRUE(has_view);
+        ASSERT_EQ(configuration->GetMetrics(0)->device_pixel_ratio, 2.0);
+        ASSERT_EQ(configuration->GetMetrics(0)->physical_width, 10.0);
+        ASSERT_EQ(configuration->GetMetrics(0)->physical_height, 20.0);
+        ASSERT_EQ(configuration->GetMetrics(0)->physical_touch_slop, 22);
+
+        message_latch->Signal();
+      };
 
   Settings settings = CreateSettingsForFixture();
   TaskRunners task_runners("test",                  // label
@@ -123,8 +114,8 @@ TEST_F(PlatformConfigurationTest, GetWindowReturnsNullForNonexistentId) {
         PlatformConfiguration* configuration =
             UIDartState::Current()->platform_configuration();
 
-        ASSERT_EQ(configuration->get_window(1), nullptr);
-        ASSERT_EQ(configuration->get_window(2), nullptr);
+        ASSERT_EQ(configuration->GetMetrics(1), nullptr);
+        ASSERT_EQ(configuration->GetMetrics(2), nullptr);
 
         message_latch->Signal();
       };
diff --git a/lib/ui/window/window.cc b/lib/ui/window/window.cc
deleted file mode 100644
index f3866f2ebc56a..0000000000000
--- a/lib/ui/window/window.cc
+++ /dev/null
@@ -1,59 +0,0 @@
-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "flutter/lib/ui/window/window.h"
-
-#include <utility>
-
-#include "third_party/tonic/converter/dart_converter.h"
-#include "third_party/tonic/dart_args.h"
-#include "third_party/tonic/logging/dart_invoke.h"
-#include "third_party/tonic/typed_data/dart_byte_data.h"
-
-namespace flutter {
-
-Window::Window(int64_t window_id, ViewportMetrics metrics)
-    : window_id_(window_id), viewport_metrics_(std::move(metrics)) {
-  library_.Set(tonic::DartState::Current(),
-               Dart_LookupLibrary(tonic::ToDart("dart:ui")));
-}
-
-Window::~Window() {}
-
-void Window::UpdateWindowMetrics(const ViewportMetrics& metrics) {
-  viewport_metrics_ = metrics;
-
-  std::shared_ptr<tonic::DartState> dart_state = library_.dart_state().lock();
-  if (!dart_state) {
-    return;
-  }
-  tonic::DartState::Scope scope(dart_state);
-  tonic::CheckAndHandleError(tonic::DartInvokeField(
-      library_.value(), "_updateWindowMetrics",
-      {
-          tonic::ToDart(window_id_),
-          tonic::ToDart(metrics.device_pixel_ratio),
-          tonic::ToDart(metrics.physical_width),
-          tonic::ToDart(metrics.physical_height),
-          tonic::ToDart(metrics.physical_padding_top),
-          tonic::ToDart(metrics.physical_padding_right),
-          tonic::ToDart(metrics.physical_padding_bottom),
-          tonic::ToDart(metrics.physical_padding_left),
-          tonic::ToDart(metrics.physical_view_inset_top),
-          tonic::ToDart(metrics.physical_view_inset_right),
-          tonic::ToDart(metrics.physical_view_inset_bottom),
-          tonic::ToDart(metrics.physical_view_inset_left),
-          tonic::ToDart(metrics.physical_system_gesture_inset_top),
-          tonic::ToDart(metrics.physical_system_gesture_inset_right),
-          tonic::ToDart(metrics.physical_system_gesture_inset_bottom),
-          tonic::ToDart(metrics.physical_system_gesture_inset_left),
-          tonic::ToDart(metrics.physical_touch_slop),
-          tonic::ToDart(metrics.physical_display_features_bounds),
-          tonic::ToDart(metrics.physical_display_features_type),
-          tonic::ToDart(metrics.physical_display_features_state),
-          tonic::ToDart(metrics.display_id),
-      }));
-}
-
-}  // namespace flutter
diff --git a/lib/ui/window/window.h b/lib/ui/window/window.h
deleted file mode 100644
index 95153f6559b7b..0000000000000
--- a/lib/ui/window/window.h
+++ /dev/null
@@ -1,41 +0,0 @@
-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef FLUTTER_LIB_UI_WINDOW_WINDOW_H_
-#define FLUTTER_LIB_UI_WINDOW_WINDOW_H_
-
-#include <functional>
-#include <string>
-#include <unordered_map>
-#include <vector>
-
-#include "flutter/lib/ui/window/key_data_packet.h"
-#include "flutter/lib/ui/window/platform_message.h"
-#include "flutter/lib/ui/window/pointer_data_packet.h"
-#include "flutter/lib/ui/window/viewport_metrics.h"
-#include "third_party/skia/include/gpu/GrDirectContext.h"
-#include "third_party/tonic/dart_persistent_value.h"
-
-namespace flutter {
-class Window final {
- public:
-  Window(int64_t window_id, ViewportMetrics metrics);
-
-  ~Window();
-
-  int window_id() const { return window_id_; }
-
-  const ViewportMetrics& viewport_metrics() const { return viewport_metrics_; }
-
-  void UpdateWindowMetrics(const ViewportMetrics& metrics);
-
- private:
-  tonic::DartPersistentValue library_;
-  int64_t window_id_;
-  ViewportMetrics viewport_metrics_;
-};
-
-}  // namespace flutter
-
-#endif  // FLUTTER_LIB_UI_WINDOW_WINDOW_H_
diff --git a/runtime/platform_data.h b/runtime/platform_data.h
index b6d4c65f94d19..f7f00e1380b76 100644
--- a/runtime/platform_data.h
+++ b/runtime/platform_data.h
@@ -32,7 +32,9 @@ struct PlatformData {
 
   ~PlatformData();
 
-  ViewportMetrics viewport_metrics;
+  // A map from view IDs of existing views to their viewport metrics.
+  std::unordered_map<int64_t, ViewportMetrics> viewport_metrics_for_views;
+
   std::string language_code;
   std::string country_code;
   std::string script_code;
diff --git a/runtime/runtime_controller.cc b/runtime/runtime_controller.cc
index 751fa696a5719..a11b9c2ff24f3 100644
--- a/runtime/runtime_controller.cc
+++ b/runtime/runtime_controller.cc
@@ -6,13 +6,14 @@
 
 #include <utility>
 
+#include "flutter/common/constants.h"
+#include "flutter/common/settings.h"
 #include "flutter/fml/message_loop.h"
 #include "flutter/fml/trace_event.h"
 #include "flutter/lib/ui/compositing/scene.h"
 #include "flutter/lib/ui/ui_dart_state.h"
 #include "flutter/lib/ui/window/platform_configuration.h"
 #include "flutter/lib/ui/window/viewport_metrics.h"
-#include "flutter/lib/ui/window/window.h"
 #include "flutter/runtime/dart_isolate_group_data.h"
 #include "flutter/runtime/isolate_configuration.h"
 #include "flutter/runtime/runtime_delegate.h"
@@ -20,8 +21,6 @@
 
 namespace flutter {
 
-constexpr uint64_t kFlutterImplicitViewId = 0ll;
-
 RuntimeController::RuntimeController(RuntimeDelegate& p_client,
                                      const TaskRunners& task_runners)
     : client_(p_client), vm_(nullptr), context_(task_runners) {}
@@ -76,7 +75,6 @@ std::unique_ptr<RuntimeController> RuntimeController::Spawn(
                                           p_persistent_isolate_data,     //
                                           spawned_context);              //
   result->spawning_isolate_ = root_isolate_;
-  result->platform_data_.viewport_metrics = ViewportMetrics();
   return result;
 }
 
@@ -115,11 +113,16 @@ std::unique_ptr<RuntimeController> RuntimeController::Clone() const {
 }
 
 bool RuntimeController::FlushRuntimeStateToIsolate() {
-  // TODO(dkwingsmt): Needs a view ID here (or platform_data should probably
-  // have multiple view metrics).
-  return SetViewportMetrics(kFlutterImplicitViewId,
-                            platform_data_.viewport_metrics) &&
-         SetLocales(platform_data_.locale_data) &&
+  FML_DCHECK(!has_flushed_runtime_state_)
+      << "FlushRuntimeStateToIsolate is called more than once somehow.";
+  has_flushed_runtime_state_ = true;
+  for (auto const& [view_id, viewport_metrics] :
+       platform_data_.viewport_metrics_for_views) {
+    if (!AddView(view_id, viewport_metrics)) {
+      return false;
+    }
+  }
+  return SetLocales(platform_data_.locale_data) &&
          SetSemanticsEnabled(platform_data_.semantics_enabled) &&
          SetAccessibilityFeatures(
              platform_data_.accessibility_feature_flags_) &&
@@ -128,19 +131,35 @@ bool RuntimeController::FlushRuntimeStateToIsolate() {
          SetDisplays(platform_data_.displays);
 }
 
+bool RuntimeController::AddView(int64_t view_id,
+                                const ViewportMetrics& view_metrics) {
+  platform_data_.viewport_metrics_for_views[view_id] = view_metrics;
+  if (auto* platform_configuration = GetPlatformConfigurationIfAvailable()) {
+    platform_configuration->AddView(view_id, view_metrics);
+
+    return true;
+  }
+
+  return false;
+}
+
+bool RuntimeController::RemoveView(int64_t view_id) {
+  platform_data_.viewport_metrics_for_views.erase(view_id);
+  if (auto* platform_configuration = GetPlatformConfigurationIfAvailable()) {
+    platform_configuration->RemoveView(view_id);
+    return true;
+  }
+
+  return false;
+}
+
 bool RuntimeController::SetViewportMetrics(int64_t view_id,
                                            const ViewportMetrics& metrics) {
   TRACE_EVENT0("flutter", "SetViewportMetrics");
-  platform_data_.viewport_metrics = metrics;
 
+  platform_data_.viewport_metrics_for_views[view_id] = metrics;
   if (auto* platform_configuration = GetPlatformConfigurationIfAvailable()) {
-    Window* window = platform_configuration->get_window(view_id);
-    if (window) {
-      window->UpdateWindowMetrics(metrics);
-      return true;
-    } else {
-      FML_LOG(WARNING) << "View ID " << view_id << " does not exist.";
-    }
+    return platform_configuration->UpdateViewMetrics(view_id, metrics);
   }
 
   return false;
@@ -311,11 +330,6 @@ RuntimeController::GetPlatformConfigurationIfAvailable() {
   return root_isolate ? root_isolate->platform_configuration() : nullptr;
 }
 
-// |PlatformConfigurationClient|
-bool RuntimeController::ImplicitViewEnabled() {
-  return client_.ImplicitViewEnabled();
-}
-
 // |PlatformConfigurationClient|
 std::string RuntimeController::DefaultRouteName() {
   return client_.DefaultRouteName();
@@ -330,15 +344,14 @@ void RuntimeController::ScheduleFrame() {
 void RuntimeController::Render(Scene* scene) {
   // TODO(dkwingsmt): Currently only supports a single window.
   int64_t view_id = kFlutterImplicitViewId;
-  auto window =
-      UIDartState::Current()->platform_configuration()->get_window(view_id);
-  if (window == nullptr) {
+  const ViewportMetrics* view_metrics =
+      UIDartState::Current()->platform_configuration()->GetMetrics(view_id);
+  if (view_metrics == nullptr) {
     return;
   }
-  const auto& viewport_metrics = window->viewport_metrics();
-  client_.Render(scene->takeLayerTree(viewport_metrics.physical_width,
-                                      viewport_metrics.physical_height),
-                 viewport_metrics.device_pixel_ratio);
+  client_.Render(scene->takeLayerTree(view_metrics->physical_width,
+                                      view_metrics->physical_height),
+                 view_metrics->device_pixel_ratio);
 }
 
 // |PlatformConfigurationClient|
diff --git a/runtime/runtime_controller.h b/runtime/runtime_controller.h
index aaef6da631694..1d1b0d7407e62 100644
--- a/runtime/runtime_controller.h
+++ b/runtime/runtime_controller.h
@@ -42,6 +42,11 @@ class Window;
 /// used by the engine to copy the currently accumulated window state so it can
 /// be referenced by the new runtime controller.
 ///
+/// When `RuntimeController` is created, it takes some time before the root
+/// isolate becomes ready. Operation during this gap is stored by
+/// `RuntimeController` and flushed to the Dart VM when the isolate becomes
+/// ready before the entrypoint function. See `PlatformData`.
+///
 class RuntimeController : public PlatformConfigurationClient {
  public:
   //----------------------------------------------------------------------------
@@ -163,6 +168,30 @@ class RuntimeController : public PlatformConfigurationClient {
   ///
   std::unique_ptr<RuntimeController> Clone() const;
 
+  //----------------------------------------------------------------------------
+  /// @brief      Notify the isolate that a new view is available.
+  ///
+  ///             A view must be added before other methods can refer to it,
+  ///             including the implicit view. Adding a view that already exists
+  ///             triggers an assertion.
+  ///
+  /// @param[in]  view_id           The ID of the new view.
+  /// @param[in]  viewport_metrics  The initial viewport metrics for the view.
+  ///
+  bool AddView(int64_t view_id, const ViewportMetrics& view_metrics);
+
+  //----------------------------------------------------------------------------
+  /// @brief      Notify the isolate that a view is no longer available.
+  ///
+  ///             Removing a view that does not exist triggers an assertion.
+  ///
+  ///             The implicit view (kFlutterImplicitViewId) should never be
+  ///             removed. Doing so triggers an assertion.
+  ///
+  /// @param[in]  view_id  The ID of the view.
+  ///
+  bool RemoveView(int64_t view_id);
+
   //----------------------------------------------------------------------------
   /// @brief      Forward the specified viewport metrics to the running isolate.
   ///             If the isolate is not running, these metrics will be saved and
@@ -616,14 +645,12 @@ class RuntimeController : public PlatformConfigurationClient {
   const fml::closure isolate_shutdown_callback_;
   std::shared_ptr<const fml::Mapping> persistent_isolate_data_;
   UIDartState::Context context_;
+  bool has_flushed_runtime_state_ = false;
 
   PlatformConfiguration* GetPlatformConfigurationIfAvailable();
 
   bool FlushRuntimeStateToIsolate();
 
-  // |PlatformConfigurationClient|
-  bool ImplicitViewEnabled() override;
-
   // |PlatformConfigurationClient|
   std::string DefaultRouteName() override;
 
diff --git a/runtime/runtime_delegate.h b/runtime/runtime_delegate.h
index 18e4dbfdfd31c..330fc46e1d6a5 100644
--- a/runtime/runtime_delegate.h
+++ b/runtime/runtime_delegate.h
@@ -21,8 +21,6 @@ namespace flutter {
 
 class RuntimeDelegate {
  public:
-  virtual bool ImplicitViewEnabled() = 0;
-
   virtual std::string DefaultRouteName() = 0;
 
   virtual void ScheduleFrame(bool regenerate_layer_tree = true) = 0;
diff --git a/shell/common/engine.cc b/shell/common/engine.cc
index 829e3fd60bed0..d87acb8b879ba 100644
--- a/shell/common/engine.cc
+++ b/shell/common/engine.cc
@@ -292,6 +292,14 @@ tonic::DartErrorHandleType Engine::GetUIIsolateLastError() {
   return runtime_controller_->GetLastError();
 }
 
+void Engine::AddView(int64_t view_id, const ViewportMetrics& view_metrics) {
+  runtime_controller_->AddView(view_id, view_metrics);
+}
+
+void Engine::RemoveView(int64_t view_id) {
+  runtime_controller_->RemoveView(view_id);
+}
+
 void Engine::SetViewportMetrics(int64_t view_id,
                                 const ViewportMetrics& metrics) {
   runtime_controller_->SetViewportMetrics(view_id, metrics);
@@ -440,14 +448,6 @@ void Engine::SetAccessibilityFeatures(int32_t flags) {
   runtime_controller_->SetAccessibilityFeatures(flags);
 }
 
-bool Engine::ImplicitViewEnabled() {
-  // TODO(loicsharma): This value should be provided by the embedder
-  // when it launches the engine. For now, assume the embedder always creates a
-  // view.
-  // See: https://github.com/flutter/flutter/issues/120306
-  return true;
-}
-
 std::string Engine::DefaultRouteName() {
   if (!initial_route_.empty()) {
     return initial_route_;
diff --git a/shell/common/engine.h b/shell/common/engine.h
index e0a4701f87b0e..e53efc9eb3882 100644
--- a/shell/common/engine.h
+++ b/shell/common/engine.h
@@ -675,6 +675,31 @@ class Engine final : public RuntimeDelegate, PointerDataDispatcher::Delegate {
   ///
   std::optional<uint32_t> GetUIIsolateReturnCode();
 
+  //----------------------------------------------------------------------------
+  /// @brief      Notify the Flutter application that a new view is available.
+  ///
+  ///             A view must be added before other methods can refer to it,
+  ///             including the implicit view. Adding a view that already exists
+  ///             triggers an assertion.
+  ///
+  /// @param[in]  view_id           The ID of the new view.
+  /// @param[in]  viewport_metrics  The initial viewport metrics for the view.
+  ///
+  void AddView(int64_t view_id, const ViewportMetrics& view_metrics);
+
+  //----------------------------------------------------------------------------
+  /// @brief      Notify the Flutter application that a view is no
+  ///             longer available.
+  ///
+  ///             Removing a view that does not exist triggers an assertion.
+  ///
+  ///             The implicit view (kFlutterImplicitViewId) should never be
+  ///             removed. Doing so triggers an assertion.
+  ///
+  /// @param[in]  view_id  The ID of the view.
+  ///
+  void RemoveView(int64_t view_id);
+
   //----------------------------------------------------------------------------
   /// @brief      Updates the viewport metrics for a view. The viewport metrics
   ///             detail the size of the rendering viewport in texels as well as
@@ -898,9 +923,6 @@ class Engine final : public RuntimeDelegate, PointerDataDispatcher::Delegate {
   const std::weak_ptr<VsyncWaiter> GetVsyncWaiter() const;
 
  private:
-  // |RuntimeDelegate|
-  bool ImplicitViewEnabled() override;
-
   // |RuntimeDelegate|
   std::string DefaultRouteName() override;
 
diff --git a/shell/common/engine_unittests.cc b/shell/common/engine_unittests.cc
index d1a7d24d39cbc..a6bbc12adb644 100644
--- a/shell/common/engine_unittests.cc
+++ b/shell/common/engine_unittests.cc
@@ -21,7 +21,6 @@
 namespace flutter {
 
 namespace {
-constexpr int64_t kImplicitViewId = 0ll;
 
 class MockDelegate : public Engine::Delegate {
  public:
@@ -319,48 +318,6 @@ TEST_F(EngineTest, SpawnWithCustomInitialRoute) {
   });
 }
 
-TEST_F(EngineTest, SpawnResetsViewportMetrics) {
-  PostUITaskSync([this] {
-    MockRuntimeDelegate client;
-    auto mock_runtime_controller =
-        std::make_unique<MockRuntimeController>(client, task_runners_);
-    auto vm_ref = DartVMRef::Create(settings_);
-    EXPECT_CALL(*mock_runtime_controller, GetDartVM())
-        .WillRepeatedly(::testing::Return(vm_ref.get()));
-    ViewportMetrics old_viewport_metrics = ViewportMetrics();
-    const double kViewWidth = 768;
-    const double kViewHeight = 1024;
-    old_viewport_metrics.physical_width = kViewWidth;
-    old_viewport_metrics.physical_height = kViewHeight;
-    mock_runtime_controller->SetViewportMetrics(kImplicitViewId,
-                                                old_viewport_metrics);
-    auto engine = std::make_unique<Engine>(
-        /*delegate=*/delegate_,
-        /*dispatcher_maker=*/dispatcher_maker_,
-        /*image_decoder_task_runner=*/image_decoder_task_runner_,
-        /*task_runners=*/task_runners_,
-        /*settings=*/settings_,
-        /*animator=*/std::move(animator_),
-        /*io_manager=*/io_manager_,
-        /*font_collection=*/std::make_shared<FontCollection>(),
-        /*runtime_controller=*/std::move(mock_runtime_controller),
-        /*gpu_disabled_switch=*/std::make_shared<fml::SyncSwitch>());
-
-    auto& old_platform_data = engine->GetRuntimeController()->GetPlatformData();
-    EXPECT_EQ(old_platform_data.viewport_metrics.physical_width, kViewWidth);
-    EXPECT_EQ(old_platform_data.viewport_metrics.physical_height, kViewHeight);
-
-    auto spawn =
-        engine->Spawn(delegate_, dispatcher_maker_, settings_, nullptr,
-                      std::string(), io_manager_, snapshot_delegate_, nullptr);
-    EXPECT_TRUE(spawn != nullptr);
-    auto& new_viewport_metrics =
-        spawn->GetRuntimeController()->GetPlatformData().viewport_metrics;
-    EXPECT_EQ(new_viewport_metrics.physical_width, 0);
-    EXPECT_EQ(new_viewport_metrics.physical_height, 0);
-  });
-}
-
 TEST_F(EngineTest, SpawnWithCustomSettings) {
   PostUITaskSync([this] {
     MockRuntimeDelegate client;
diff --git a/shell/common/fixtures/shell_test.dart b/shell/common/fixtures/shell_test.dart
index ea7361915d7c7..e4b0d98833f44 100644
--- a/shell/common/fixtures/shell_test.dart
+++ b/shell/common/fixtures/shell_test.dart
@@ -482,3 +482,68 @@ Future<void> testThatAssetLoadingHappensOnWorkerThread() async {
   } catch (err) { /* Do nothing */ }
   notifyNative();
 }
+
+@pragma('vm:external-name', 'NativeReportViewIdsCallback')
+external void nativeReportViewIdsCallback(bool hasImplicitView, List<int> viewIds);
+
+List<int> getCurrentViewIds() {
+  final List<int> result = PlatformDispatcher.instance.views
+      .map((FlutterView view) => view.viewId)
+      .toList()
+      ..sort();
+  assert(result.toSet().length == result.length,
+      'Unexpected duplicate view ID found: $result');
+  return result;
+}
+
+bool listEquals<T>(List<T> a, List<T> b) {
+  if (a.length != b.length) {
+    return false;
+  }
+  for (int i = 0; i < a.length; i += 1) {
+    if (a[i] != b[i]) {
+      return false;
+    }
+  }
+  return true;
+}
+
+// This entrypoint reports whether there's an implicit view and the list of view
+// IDs using nativeReportViewIdsCallback on initialization and every time the
+// list of view IDs changes.
+@pragma('vm:entry-point')
+void testReportViewIds() {
+  List<int> viewIds = getCurrentViewIds();
+  nativeReportViewIdsCallback(PlatformDispatcher.instance.implicitView != null, viewIds);
+  PlatformDispatcher.instance.onMetricsChanged = () {
+    final List<int> newViewIds = getCurrentViewIds();
+    if (!listEquals(viewIds, newViewIds)) {
+      viewIds = newViewIds;
+      nativeReportViewIdsCallback(PlatformDispatcher.instance.implicitView != null, viewIds);
+    }
+  };
+}
+
+// Returns a list of [view_id 1, view_width 1, view_id 2, view_width 2, ...]
+// for all views.
+List<int> getCurrentViewWidths() {
+  final List<int> result = <int>[];
+  for (final FlutterView view in PlatformDispatcher.instance.views) {
+    result.add(view.viewId);
+    result.add(view.physicalGeometry.width.round());
+  }
+  return result;
+}
+
+@pragma('vm:external-name', 'NativeReportViewWidthsCallback')
+external void nativeReportViewWidthsCallback(List<int> viewWidthPacket);
+
+// This entrypoint reports the list of views and their widths using
+// nativeReportViewWidthsCallback on initialization and every onMetricsChanged.
+@pragma('vm:entry-point')
+void testReportViewWidths() {
+  nativeReportViewWidthsCallback(getCurrentViewWidths());
+  PlatformDispatcher.instance.onMetricsChanged = () {
+    nativeReportViewWidthsCallback(getCurrentViewWidths());
+  };
+}
diff --git a/shell/common/rasterizer.cc b/shell/common/rasterizer.cc
index d7d1338c1a533..7cc45fa1f5b5a 100644
--- a/shell/common/rasterizer.cc
+++ b/shell/common/rasterizer.cc
@@ -9,6 +9,7 @@
 #include <utility>
 
 #include "flow/frame_timings.h"
+#include "flutter/common/constants.h"
 #include "flutter/common/graphics/persistent_cache.h"
 #include "flutter/flow/layers/offscreen_surface.h"
 #include "flutter/fml/time/time_delta.h"
@@ -156,6 +157,14 @@ void Rasterizer::NotifyLowMemoryWarning() const {
   context->performDeferredCleanup(std::chrono::milliseconds(0));
 }
 
+void Rasterizer::CollectView(int64_t view_id) {
+  // TODO(dkwingsmt): When Rasterizer supports multi-view, this method should
+  // correctly clear the view corresponding to the ID.
+  if (view_id == kFlutterImplicitViewId) {
+    last_layer_tree_.reset();
+  }
+}
+
 std::shared_ptr<flutter::TextureRegistry> Rasterizer::GetTextureRegistry() {
   return compositor_context_->texture_registry();
 }
@@ -201,11 +210,14 @@ RasterStatus Rasterizer::Draw(
   RasterStatus raster_status = RasterStatus::kFailed;
   LayerTreePipeline::Consumer consumer =
       [&](std::unique_ptr<LayerTreeItem> item) {
+        // TODO(dkwingsmt): Use a proper view ID when Rasterizer supports
+        // multi-view.
+        int64_t view_id = kFlutterImplicitViewId;
         std::unique_ptr<LayerTree> layer_tree = std::move(item->layer_tree);
         std::unique_ptr<FrameTimingsRecorder> frame_timings_recorder =
             std::move(item->frame_timings_recorder);
         float device_pixel_ratio = item->device_pixel_ratio;
-        if (discard_callback(*layer_tree.get())) {
+        if (discard_callback(view_id, *layer_tree.get())) {
           raster_status = RasterStatus::kDiscarded;
         } else {
           raster_status = DoDraw(std::move(frame_timings_recorder),
diff --git a/shell/common/rasterizer.h b/shell/common/rasterizer.h
index b17242342c084..bb05e4475f998 100644
--- a/shell/common/rasterizer.h
+++ b/shell/common/rasterizer.h
@@ -204,6 +204,19 @@ class Rasterizer final : public SnapshotDelegate,
 
   fml::TaskRunnerAffineWeakPtr<SnapshotDelegate> GetSnapshotDelegate() const;
 
+  //----------------------------------------------------------------------------
+  /// @brief      Deallocate the resources for displaying a view.
+  ///
+  ///             This method should be called when a view is removed.
+  ///
+  ///             The rasterizer don't need views to be registered. Last-frame
+  ///             states for views are recorded when layer trees are rasterized
+  ///             to the view and used during `Rasterizer::DrawLastLayerTree`.
+  ///
+  /// @param[in]  view_id  The ID of the view.
+  ///
+  void CollectView(int64_t view_id);
+
   //----------------------------------------------------------------------------
   /// @brief      Sometimes, it may be necessary to render the same frame again
   ///             without having to wait for the framework to build a whole new
@@ -240,7 +253,8 @@ class Rasterizer final : public SnapshotDelegate,
 
   std::shared_ptr<flutter::TextureRegistry> GetTextureRegistry() override;
 
-  using LayerTreeDiscardCallback = std::function<bool(flutter::LayerTree&)>;
+  using LayerTreeDiscardCallback =
+      std::function<bool(int64_t, flutter::LayerTree&)>;
 
   //----------------------------------------------------------------------------
   /// @brief      Takes the next item from the layer tree pipeline and executes
@@ -569,7 +583,9 @@ class Rasterizer final : public SnapshotDelegate,
 
   void FireNextFrameCallbackIfPresent();
 
-  static bool NoDiscard(const flutter::LayerTree& layer_tree) { return false; }
+  static bool NoDiscard(int64_t view_id, const flutter::LayerTree& layer_tree) {
+    return false;
+  }
   static bool ShouldResubmitFrame(const RasterStatus& raster_status);
 
   Delegate& delegate_;
diff --git a/shell/common/rasterizer_unittests.cc b/shell/common/rasterizer_unittests.cc
index 5307dcacccfdf..55694a4554278 100644
--- a/shell/common/rasterizer_unittests.cc
+++ b/shell/common/rasterizer_unittests.cc
@@ -29,6 +29,7 @@ using testing::ReturnRef;
 
 namespace flutter {
 namespace {
+
 constexpr float kDevicePixelRatio = 2.0f;
 
 class MockDelegate : public Rasterizer::Delegate {
@@ -41,7 +42,6 @@ class MockDelegate : public Rasterizer::Delegate {
                      const fml::RefPtr<fml::RasterThreadMerger>());
   MOCK_CONST_METHOD0(GetIsGpuDisabledSyncSwitch,
                      std::shared_ptr<const fml::SyncSwitch>());
-  MOCK_METHOD0(CreateSnapshotSurface, std::unique_ptr<Surface>());
   MOCK_CONST_METHOD0(GetSettings, const Settings&());
 };
 
@@ -199,7 +199,7 @@ TEST(RasterizerTest,
     PipelineProduceResult result =
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     rasterizer->Draw(pipeline, no_discard);
     latch.Signal();
   });
@@ -265,7 +265,7 @@ TEST(
     PipelineProduceResult result =
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     rasterizer->Draw(pipeline, no_discard);
     latch.Signal();
   });
@@ -336,7 +336,7 @@ TEST(
   PipelineProduceResult result =
       pipeline->Produce().Complete(std::move(layer_tree_item));
   EXPECT_TRUE(result.success);
-  auto no_discard = [](LayerTree&) { return false; };
+  auto no_discard = [](int64_t, LayerTree&) { return false; };
   rasterizer->Draw(pipeline, no_discard);
 }
 
@@ -410,7 +410,7 @@ TEST(RasterizerTest,
   PipelineProduceResult result =
       pipeline->Produce().Complete(std::move(layer_tree_item));
   EXPECT_TRUE(result.success);
-  auto no_discard = [](LayerTree&) { return false; };
+  auto no_discard = [](int64_t, LayerTree&) { return false; };
 
   // The Draw() will respectively call BeginFrame(), SubmitFrame() and
   // EndFrame() one time.
@@ -460,7 +460,7 @@ TEST(RasterizerTest, externalViewEmbedderDoesntEndFrameWhenNoSurfaceIsSet) {
     PipelineProduceResult result =
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     rasterizer->Draw(pipeline, no_discard);
     latch.Signal();
   });
@@ -517,7 +517,7 @@ TEST(RasterizerTest, externalViewEmbedderDoesntEndFrameWhenNotUsedThisFrame) {
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
     // Always discard the layer tree.
-    auto discard_callback = [](LayerTree&) { return true; };
+    auto discard_callback = [](int64_t, LayerTree&) { return true; };
     RasterStatus status = rasterizer->Draw(pipeline, discard_callback);
     EXPECT_EQ(status, RasterStatus::kDiscarded);
     latch.Signal();
@@ -561,7 +561,7 @@ TEST(RasterizerTest, externalViewEmbedderDoesntEndFrameWhenPipelineIsEmpty) {
   fml::AutoResetWaitableEvent latch;
   thread_host.raster_thread->GetTaskRunner()->PostTask([&] {
     auto pipeline = std::make_shared<LayerTreePipeline>(/*depth=*/10);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     RasterStatus status = rasterizer->Draw(pipeline, no_discard);
     EXPECT_EQ(status, RasterStatus::kFailed);
     latch.Signal();
@@ -619,7 +619,7 @@ TEST(RasterizerTest,
     PipelineProduceResult result =
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     rasterizer->Draw(pipeline, no_discard);
     latch.Signal();
   });
@@ -677,7 +677,7 @@ TEST(
     PipelineProduceResult result =
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     RasterStatus status = rasterizer->Draw(pipeline, no_discard);
     EXPECT_EQ(status, RasterStatus::kSuccess);
     latch.Signal();
@@ -735,7 +735,7 @@ TEST(
     PipelineProduceResult result =
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     RasterStatus status = rasterizer->Draw(pipeline, no_discard);
     EXPECT_EQ(status, RasterStatus::kSuccess);
     latch.Signal();
@@ -792,7 +792,7 @@ TEST(
     PipelineProduceResult result =
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     RasterStatus status = rasterizer->Draw(pipeline, no_discard);
     EXPECT_EQ(status, RasterStatus::kDiscarded);
     latch.Signal();
@@ -848,7 +848,7 @@ TEST(
     PipelineProduceResult result =
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     RasterStatus status = rasterizer->Draw(pipeline, no_discard);
     EXPECT_EQ(status, RasterStatus::kFailed);
     latch.Signal();
@@ -929,7 +929,7 @@ TEST(RasterizerTest,
       EXPECT_TRUE(result.success);
       EXPECT_EQ(result.is_first_item, i == 0);
     }
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     // Although we only call 'Rasterizer::Draw' once, it will be called twice
     // finally because there are two items in the pipeline.
     rasterizer->Draw(pipeline, no_discard);
@@ -1100,7 +1100,7 @@ TEST(RasterizerTest, presentationTimeSetWhenVsyncTargetInFuture) {
       EXPECT_TRUE(result.success);
       EXPECT_EQ(result.is_first_item, i == 0);
     }
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     // Although we only call 'Rasterizer::Draw' once, it will be called twice
     // finally because there are two items in the pipeline.
     rasterizer->Draw(pipeline, no_discard);
@@ -1181,7 +1181,7 @@ TEST(RasterizerTest, presentationTimeNotSetWhenVsyncTargetInPast) {
         pipeline->Produce().Complete(std::move(layer_tree_item));
     EXPECT_TRUE(result.success);
     EXPECT_EQ(result.is_first_item, true);
-    auto no_discard = [](LayerTree&) { return false; };
+    auto no_discard = [](int64_t, LayerTree&) { return false; };
     rasterizer->Draw(pipeline, no_discard);
   });
 
diff --git a/shell/common/shell.cc b/shell/common/shell.cc
index 136c09b9c39d0..7964a530031db 100644
--- a/shell/common/shell.cc
+++ b/shell/common/shell.cc
@@ -11,6 +11,7 @@
 #include <vector>
 
 #include "flutter/assets/directory_asset_bundle.h"
+#include "flutter/common/constants.h"
 #include "flutter/common/graphics/persistent_cache.h"
 #include "flutter/fml/base32.h"
 #include "flutter/fml/file.h"
@@ -715,6 +716,7 @@ bool Shell::Setup(std::unique_ptr<PlatformView> platform_view,
   weak_rasterizer_ = rasterizer_->GetWeakPtr();
   weak_platform_view_ = platform_view_->GetWeakPtr();
 
+  engine_->AddView(kFlutterImplicitViewId, ViewportMetrics{});
   // Setup the time-consuming default font manager right after engine created.
   if (!settings_.prefetched_default_font_manager) {
     fml::TaskRunner::RunNowOrPostTask(task_runners_.GetUITaskRunner(),
@@ -808,10 +810,11 @@ void Shell::OnPlatformViewCreated(std::unique_ptr<Surface> surface) {
       !task_runners_.GetRasterTaskRunner()->RunsTasksOnCurrentThread();
 
   fml::AutoResetWaitableEvent latch;
-  auto raster_task =
-      fml::MakeCopyable([&waiting_for_first_frame = waiting_for_first_frame_,
-                         rasterizer = rasterizer_->GetWeakPtr(),  //
-                         surface = std::move(surface)]() mutable {
+  auto raster_task = fml::MakeCopyable(
+      [&waiting_for_first_frame = waiting_for_first_frame_,  //
+       rasterizer = rasterizer_->GetWeakPtr(),               //
+       surface = std::move(surface)                          //
+  ]() mutable {
         if (rasterizer) {
           // Enables the thread merger which may be used by the external view
           // embedder.
@@ -989,7 +992,7 @@ void Shell::OnPlatformViewSetViewportMetrics(int64_t view_id,
 
   {
     std::scoped_lock<std::mutex> lock(resize_mutex_);
-    expected_frame_size_ =
+    expected_frame_sizes_[view_id] =
         SkISize::Make(metrics.physical_width, metrics.physical_height);
     device_pixel_ratio_ = metrics.device_pixel_ratio;
   }
@@ -1215,10 +1218,11 @@ void Shell::OnAnimatorUpdateLatestFrameTargetTime(
 void Shell::OnAnimatorDraw(std::shared_ptr<LayerTreePipeline> pipeline) {
   FML_DCHECK(is_set_up_);
 
-  auto discard_callback = [this](flutter::LayerTree& tree) {
+  auto discard_callback = [this](int64_t view_id, flutter::LayerTree& tree) {
     std::scoped_lock<std::mutex> lock(resize_mutex_);
-    return !expected_frame_size_.isEmpty() &&
-           tree.frame_size() != expected_frame_size_;
+    auto expected_frame_size = ExpectedFrameSize(view_id);
+    return !expected_frame_size.isEmpty() &&
+           tree.frame_size() != expected_frame_size;
   };
 
   task_runners_.GetRasterTaskRunner()->PostTask(fml::MakeCopyable(
@@ -1940,6 +1944,9 @@ bool Shell::OnServiceProtocolRenderFrameWithRasterStats(
     rapidjson::Document* response) {
   FML_DCHECK(task_runners_.GetRasterTaskRunner()->RunsTasksOnCurrentThread());
 
+  // TODO(dkwingsmt): This method only handles view #0, including the snapshot
+  // and the frame size. We need to adapt this method to multi-view.
+  // https://github.com/flutter/flutter/issues/131892
   if (auto last_layer_tree = rasterizer_->GetLastLayerTree()) {
     auto& allocator = response->GetAllocator();
     response->SetObject();
@@ -1971,7 +1978,7 @@ bool Shell::OnServiceProtocolRenderFrameWithRasterStats(
 
     response->AddMember("snapshots", snapshots, allocator);
 
-    const auto& frame_size = expected_frame_size_;
+    const auto& frame_size = ExpectedFrameSize(kFlutterImplicitViewId);
     response->AddMember("frame_width", frame_size.width(), allocator);
     response->AddMember("frame_height", frame_size.height(), allocator);
 
@@ -2027,6 +2034,54 @@ bool Shell::OnServiceProtocolReloadAssetFonts(
   return true;
 }
 
+void Shell::AddView(int64_t view_id, const ViewportMetrics& viewport_metrics) {
+  TRACE_EVENT0("flutter", "Shell::AddView");
+  FML_DCHECK(is_set_up_);
+  FML_DCHECK(task_runners_.GetPlatformTaskRunner()->RunsTasksOnCurrentThread());
+  FML_DCHECK(view_id != kFlutterImplicitViewId)
+      << "Unexpected request to add the implicit view #"
+      << kFlutterImplicitViewId << ". This view should never be added.";
+
+  task_runners_.GetUITaskRunner()->PostTask([engine = engine_->GetWeakPtr(),  //
+                                             viewport_metrics,                //
+                                             view_id                          //
+  ] {
+    if (engine) {
+      engine->AddView(view_id, viewport_metrics);
+    }
+  });
+}
+
+void Shell::RemoveView(int64_t view_id) {
+  TRACE_EVENT0("flutter", "Shell::RemoveView");
+  FML_DCHECK(is_set_up_);
+  FML_DCHECK(task_runners_.GetPlatformTaskRunner()->RunsTasksOnCurrentThread());
+  FML_DCHECK(view_id != kFlutterImplicitViewId)
+      << "Unexpected request to remove the implicit view #"
+      << kFlutterImplicitViewId << ". This view should never be removed.";
+
+  expected_frame_sizes_.erase(view_id);
+  task_runners_.GetUITaskRunner()->PostTask(
+      [&task_runners = task_runners_,           //
+       engine = engine_->GetWeakPtr(),          //
+       rasterizer = rasterizer_->GetWeakPtr(),  //
+       view_id                                  //
+  ] {
+        if (engine) {
+          engine->RemoveView(view_id);
+        }
+        // Don't wait for the raster task here, which only cleans up memory and
+        // does not affect functionality. Make sure it is done after Dart
+        // removes the view to avoid receiving another rasterization request
+        // that adds back the view record.
+        task_runners.GetRasterTaskRunner()->PostTask([rasterizer, view_id]() {
+          if (rasterizer) {
+            rasterizer->CollectView(view_id);
+          }
+        });
+      });
+}
+
 Rasterizer::Screenshot Shell::Screenshot(
     Rasterizer::ScreenshotType screenshot_type,
     bool base64_encode) {
@@ -2167,4 +2222,12 @@ Shell::GetConcurrentWorkerTaskRunner() const {
   return vm_->GetConcurrentWorkerTaskRunner();
 }
 
+SkISize Shell::ExpectedFrameSize(int64_t view_id) {
+  auto found = expected_frame_sizes_.find(view_id);
+  if (found == expected_frame_sizes_.end()) {
+    return SkISize::MakeEmpty();
+  }
+  return found->second;
+}
+
 }  // namespace flutter
diff --git a/shell/common/shell.h b/shell/common/shell.h
index 23689332233c9..c4b585550b082 100644
--- a/shell/common/shell.h
+++ b/shell/common/shell.h
@@ -298,6 +298,37 @@ class Shell final : public PlatformView::Delegate,
   ///
   bool IsSetup() const;
 
+  /// @brief  Allocates resources for a new non-implicit view.
+  ///
+  ///         This method returns immediately and does not wait for the task on
+  ///         the UI thread to finish. This is safe because operations are
+  ///         either initiated from the UI thread (such as rendering), or are
+  ///         sent as posted tasks that are queued. In either case, it's ok for
+  ///         the engine to have views that the Dart VM doesn't.
+  ///
+  ///         The implicit view should never be added with this function.
+  ///         Instead, it is added internally on Shell initialization. Trying to
+  ///         add `kFlutterImplicitViewId` triggers an assertion.
+  ///
+  /// @param[in]  view_id           The view ID of the new view.
+  /// @param[in]  viewport_metrics  The initial viewport metrics for the view.
+  ///
+  void AddView(int64_t view_id, const ViewportMetrics& viewport_metrics);
+
+  /// @brief  Deallocates resources for a non-implicit view.
+  ///
+  ///         This method returns immediately and does not wait for the task on
+  ///         the UI thread to finish. This means that the Dart VM might still
+  ///         send messages regarding this view ID for a short while, even
+  ///         though this view ID is already invalid.
+  ///
+  ///         The implicit view should never be removed. Trying to remove
+  ///         `kFlutterImplicitViewId` triggers an assertion.
+  ///
+  /// @param[in]  view_id     The view ID of the view to be removed.
+  ///
+  void RemoveView(int64_t view_id);
+
   //----------------------------------------------------------------------------
   /// @brief      Captures a screenshot and optionally Base64 encodes the data
   ///             of the last layer tree rendered by the rasterizer in this
@@ -479,7 +510,7 @@ class Shell final : public PlatformView::Delegate,
   std::mutex resize_mutex_;
 
   // used to discard wrong size layer tree produced during interactive resizing
-  SkISize expected_frame_size_ = SkISize::MakeEmpty();
+  std::unordered_map<int64_t, SkISize> expected_frame_sizes_;
 
   // Used to communicate the right frame bounds via service protocol.
   double device_pixel_ratio_ = 0.0;
@@ -741,6 +772,8 @@ class Shell final : public PlatformView::Delegate,
   // directory.
   std::unique_ptr<DirectoryAssetBundle> RestoreOriginalAssetResolver();
 
+  SkISize ExpectedFrameSize(int64_t view_id);
+
   // For accessing the Shell via the raster thread, necessary for various
   // rasterizer callbacks.
   std::unique_ptr<fml::TaskRunnerAffineWeakPtrFactory<Shell>> weak_factory_gpu_;
diff --git a/shell/common/shell_test_platform_view_vulkan.h b/shell/common/shell_test_platform_view_vulkan.h
index 718f7fe6dec06..e617ea3f7f9e2 100644
--- a/shell/common/shell_test_platform_view_vulkan.h
+++ b/shell/common/shell_test_platform_view_vulkan.h
@@ -43,6 +43,7 @@ class ShellTestPlatformViewVulkan : public ShellTestPlatformView {
     // |Surface|
     std::unique_ptr<SurfaceFrame> AcquireFrame(const SkISize& size) override;
 
+    // |Surface|
     SkMatrix GetRootTransformation() const override;
 
     // |Surface|
diff --git a/shell/common/shell_unittests.cc b/shell/common/shell_unittests.cc
index cdfaf54961088..43a14bb13b75f 100644
--- a/shell/common/shell_unittests.cc
+++ b/shell/common/shell_unittests.cc
@@ -4376,6 +4376,197 @@ TEST_F(ShellTest, DiesIfSoftwareRenderingAndImpellerAreEnabledDeathTest) {
 #endif  // OS_FUCHSIA
 }
 
+// Parse the arguments of NativeReportViewIdsCallback and
+// store them in hasImplicitView and viewIds.
+static void ParseViewIdsCallback(const Dart_NativeArguments& args,
+                                 bool* hasImplicitView,
+                                 std::vector<int64_t>* viewIds) {
+  Dart_Handle exception = nullptr;
+  viewIds->clear();
+  *hasImplicitView =
+      tonic::DartConverter<bool>::FromArguments(args, 0, exception);
+  ASSERT_EQ(exception, nullptr);
+  *viewIds = tonic::DartConverter<std::vector<int64_t>>::FromArguments(
+      args, 1, exception);
+  ASSERT_EQ(exception, nullptr);
+}
+
+// Run the given task in the platform runner, and blocks until its finished.
+static void RunOnPlatformTaskRunner(Shell& shell, const fml::closure& task) {
+  fml::AutoResetWaitableEvent latch;
+  fml::TaskRunner::RunNowOrPostTask(
+      shell.GetTaskRunners().GetPlatformTaskRunner(), [&task, &latch]() {
+        task();
+        latch.Signal();
+      });
+  latch.Wait();
+}
+
+TEST_F(ShellTest, ShellStartsWithImplicitView) {
+  ASSERT_FALSE(DartVMRef::IsInstanceRunning());
+  Settings settings = CreateSettingsForFixture();
+  auto task_runner = CreateNewThread();
+  TaskRunners task_runners("test", task_runner, task_runner, task_runner,
+                           task_runner);
+  std::unique_ptr<Shell> shell = CreateShell(settings, task_runners);
+  ASSERT_TRUE(shell);
+
+  bool hasImplicitView;
+  std::vector<int64_t> viewIds;
+  fml::AutoResetWaitableEvent reportLatch;
+  auto nativeViewIdsCallback = [&reportLatch, &hasImplicitView,
+                                &viewIds](Dart_NativeArguments args) {
+    ParseViewIdsCallback(args, &hasImplicitView, &viewIds);
+    reportLatch.Signal();
+  };
+  AddNativeCallback("NativeReportViewIdsCallback",
+                    CREATE_NATIVE_ENTRY(nativeViewIdsCallback));
+
+  PlatformViewNotifyCreated(shell.get());
+  auto configuration = RunConfiguration::InferFromSettings(settings);
+  configuration.SetEntrypoint("testReportViewIds");
+  RunEngine(shell.get(), std::move(configuration));
+  reportLatch.Wait();
+
+  ASSERT_TRUE(hasImplicitView);
+  ASSERT_EQ(viewIds.size(), 1u);
+  ASSERT_EQ(viewIds[0], 0ll);
+
+  PlatformViewNotifyDestroyed(shell.get());
+  DestroyShell(std::move(shell), task_runners);
+}
+
+// Tests that Shell::AddView and Shell::RemoveView works.
+TEST_F(ShellTest, ShellCanAddViewOrRemoveView) {
+  ASSERT_FALSE(DartVMRef::IsInstanceRunning());
+  Settings settings = CreateSettingsForFixture();
+  ThreadHost thread_host(ThreadHost::ThreadHostConfig(
+      "io.flutter.test." + GetCurrentTestName() + ".",
+      ThreadHost::Type::Platform | ThreadHost::Type::RASTER |
+          ThreadHost::Type::IO | ThreadHost::Type::UI));
+  TaskRunners task_runners("test", thread_host.platform_thread->GetTaskRunner(),
+                           thread_host.raster_thread->GetTaskRunner(),
+                           thread_host.ui_thread->GetTaskRunner(),
+                           thread_host.io_thread->GetTaskRunner());
+  std::unique_ptr<Shell> shell = CreateShell(settings, task_runners);
+  ASSERT_TRUE(shell);
+
+  bool hasImplicitView;
+  std::vector<int64_t> viewIds;
+  fml::AutoResetWaitableEvent reportLatch;
+  auto nativeViewIdsCallback = [&reportLatch, &hasImplicitView,
+                                &viewIds](Dart_NativeArguments args) {
+    ParseViewIdsCallback(args, &hasImplicitView, &viewIds);
+    reportLatch.Signal();
+  };
+  AddNativeCallback("NativeReportViewIdsCallback",
+                    CREATE_NATIVE_ENTRY(nativeViewIdsCallback));
+
+  PlatformViewNotifyCreated(shell.get());
+  auto configuration = RunConfiguration::InferFromSettings(settings);
+  configuration.SetEntrypoint("testReportViewIds");
+  RunEngine(shell.get(), std::move(configuration));
+
+  reportLatch.Wait();
+  ASSERT_TRUE(hasImplicitView);
+  ASSERT_EQ(viewIds.size(), 1u);
+  ASSERT_EQ(viewIds[0], 0ll);
+
+  RunOnPlatformTaskRunner(*shell,
+                          [&shell] { shell->AddView(2, ViewportMetrics{}); });
+  reportLatch.Wait();
+  ASSERT_TRUE(hasImplicitView);
+  ASSERT_EQ(viewIds.size(), 2u);
+  ASSERT_EQ(viewIds[1], 2ll);
+
+  RunOnPlatformTaskRunner(*shell, [&shell] { shell->RemoveView(2); });
+  reportLatch.Wait();
+  ASSERT_TRUE(hasImplicitView);
+  ASSERT_EQ(viewIds.size(), 1u);
+  ASSERT_EQ(viewIds[0], 0ll);
+
+  RunOnPlatformTaskRunner(*shell,
+                          [&shell] { shell->AddView(4, ViewportMetrics{}); });
+  reportLatch.Wait();
+  ASSERT_TRUE(hasImplicitView);
+  ASSERT_EQ(viewIds.size(), 2u);
+  ASSERT_EQ(viewIds[1], 4ll);
+
+  PlatformViewNotifyDestroyed(shell.get());
+  DestroyShell(std::move(shell), task_runners);
+}
+
+// Parse the arguments of NativeReportViewWidthsCallback and
+// store them in viewWidths.
+static void ParseViewWidthsCallback(const Dart_NativeArguments& args,
+                                    std::map<int64_t, int64_t>* viewWidths) {
+  Dart_Handle exception = nullptr;
+  viewWidths->clear();
+  std::vector<int64_t> viewWidthPacket =
+      tonic::DartConverter<std::vector<int64_t>>::FromArguments(args, 0,
+                                                                exception);
+  ASSERT_EQ(exception, nullptr);
+  ASSERT_EQ(viewWidthPacket.size() % 2, 0ul);
+  for (size_t packetIndex = 0; packetIndex < viewWidthPacket.size();
+       packetIndex += 2) {
+    (*viewWidths)[viewWidthPacket[packetIndex]] =
+        viewWidthPacket[packetIndex + 1];
+  }
+}
+
+// Ensure that PlatformView::SetViewportMetrics and Shell::AddView that were
+// dispatched before the isolate is run have been flushed to the Dart VM when
+// the main function starts.
+TEST_F(ShellTest, ShellFlushesPlatformStatesByMain) {
+  ASSERT_FALSE(DartVMRef::IsInstanceRunning());
+  Settings settings = CreateSettingsForFixture();
+  ThreadHost thread_host(ThreadHost::ThreadHostConfig(
+      "io.flutter.test." + GetCurrentTestName() + ".",
+      ThreadHost::Type::Platform | ThreadHost::Type::RASTER |
+          ThreadHost::Type::IO | ThreadHost::Type::UI));
+  TaskRunners task_runners("test", thread_host.platform_thread->GetTaskRunner(),
+                           thread_host.raster_thread->GetTaskRunner(),
+                           thread_host.ui_thread->GetTaskRunner(),
+                           thread_host.io_thread->GetTaskRunner());
+  std::unique_ptr<Shell> shell = CreateShell(settings, task_runners);
+  ASSERT_TRUE(shell);
+
+  RunOnPlatformTaskRunner(*shell, [&shell] {
+    auto platform_view = shell->GetPlatformView();
+    // The construtor for ViewportMetrics{_, width, _, _, _} (only the 2nd
+    // argument matters in this test).
+    platform_view->SetViewportMetrics(0, ViewportMetrics{1, 10, 1, 0, 0});
+    shell->AddView(1, ViewportMetrics{1, 30, 1, 0, 0});
+    platform_view->SetViewportMetrics(0, ViewportMetrics{1, 20, 1, 0, 0});
+  });
+
+  bool first_report = true;
+  std::map<int64_t, int64_t> viewWidths;
+  fml::AutoResetWaitableEvent reportLatch;
+  auto nativeViewWidthsCallback = [&reportLatch, &viewWidths,
+                                   &first_report](Dart_NativeArguments args) {
+    EXPECT_TRUE(first_report);
+    first_report = false;
+    ParseViewWidthsCallback(args, &viewWidths);
+    reportLatch.Signal();
+  };
+  AddNativeCallback("NativeReportViewWidthsCallback",
+                    CREATE_NATIVE_ENTRY(nativeViewWidthsCallback));
+
+  PlatformViewNotifyCreated(shell.get());
+  auto configuration = RunConfiguration::InferFromSettings(settings);
+  configuration.SetEntrypoint("testReportViewWidths");
+  RunEngine(shell.get(), std::move(configuration));
+
+  reportLatch.Wait();
+  EXPECT_EQ(viewWidths.size(), 2u);
+  EXPECT_EQ(viewWidths[0], 20ll);
+  EXPECT_EQ(viewWidths[1], 30ll);
+
+  PlatformViewNotifyDestroyed(shell.get());
+  DestroyShell(std::move(shell), task_runners);
+}
+
 }  // namespace testing
 }  // namespace flutter
 
diff --git a/shell/platform/android/platform_view_android_jni_impl.cc b/shell/platform/android/platform_view_android_jni_impl.cc
index 7b9b2e12b37cf..b755e4f4d2ed0 100644
--- a/shell/platform/android/platform_view_android_jni_impl.cc
+++ b/shell/platform/android/platform_view_android_jni_impl.cc
@@ -17,7 +17,7 @@
 #include "unicode/uchar.h"
 
 #include "flutter/assets/directory_asset_bundle.h"
-#include "flutter/common/settings.h"
+#include "flutter/common/constants.h"
 #include "flutter/fml/file.h"
 #include "flutter/fml/mapping.h"
 #include "flutter/fml/native_library.h"
@@ -41,8 +41,6 @@
 
 namespace flutter {
 
-static constexpr int64_t kFlutterImplicitViewId = 0ll;
-
 static fml::jni::ScopedJavaGlobalRef<jclass>* g_flutter_callback_info_class =
     nullptr;
 
diff --git a/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm b/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
index 6759626b39eff..b300714f166ad 100644
--- a/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
+++ b/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
@@ -8,6 +8,7 @@
 
 #include <memory>
 
+#include "flutter/common/constants.h"
 #include "flutter/fml/message_loop.h"
 #include "flutter/fml/platform/darwin/platform_version.h"
 #include "flutter/fml/trace_event.h"
@@ -39,8 +40,6 @@
 #import "flutter/shell/platform/darwin/ios/rendering_api_selection.h"
 #include "flutter/shell/profiling/sampling_profiler.h"
 
-static constexpr int64_t kFlutterImplicitViewId = 0ll;
-
 /// Inheriting ThreadConfigurer and use iOS platform thread API to configure the thread priorities
 /// Using iOS platform thread API to configure thread priority
 static void IOSPlatformThreadConfigSetter(const fml::Thread::ThreadConfig& config) {
@@ -333,7 +332,7 @@ - (void)updateViewportMetrics:(flutter::ViewportMetrics)viewportMetrics {
   if (!self.platformView) {
     return;
   }
-  self.platformView->SetViewportMetrics(kFlutterImplicitViewId, viewportMetrics);
+  self.platformView->SetViewportMetrics(flutter::kFlutterImplicitViewId, viewportMetrics);
 }
 
 - (void)dispatchPointerDataPacket:(std::unique_ptr<flutter::PointerDataPacket>)packet {
diff --git a/shell/platform/fuchsia/flutter/platform_view.cc b/shell/platform/fuchsia/flutter/platform_view.cc
index 22fd9dbfa854c..0074361fafda8 100644
--- a/shell/platform/fuchsia/flutter/platform_view.cc
+++ b/shell/platform/fuchsia/flutter/platform_view.cc
@@ -17,7 +17,6 @@
 #include "flutter/fml/logging.h"
 #include "flutter/fml/make_copyable.h"
 #include "flutter/lib/ui/window/pointer_data.h"
-#include "flutter/lib/ui/window/window.h"
 #include "flutter/shell/platform/common/client_wrapper/include/flutter/encodable_value.h"
 #include "flutter/shell/platform/common/client_wrapper/include/flutter/standard_message_codec.h"
 #include "third_party/rapidjson/include/rapidjson/document.h"