[various] Prepare plugin repo for binding API improvements

packages/camera/camera/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.8.1+4
+
+* Silenced warnings that may occur during build when using a very
+  recent version of Flutter relating to null safety.
+
 ## 0.8.1+3
 
 * Do not change camera orientation when iOS device is flat.

packages/camera/camera/example/lib/main.dart

@@ -98,7 +98,7 @@ class _CameraExampleHomeState extends State<CameraExampleHome>
 
   @override
   void dispose() {
-    WidgetsBinding.instance?.removeObserver(this);
+    _ambiguate(WidgetsBinding.instance)?.removeObserver(this);
     _flashModeControlRowAnimationController.dispose();
     _exposureModeControlRowAnimationController.dispose();
     super.dispose();

packages/camera/camera/pubspec.yaml

@@ -4,7 +4,7 @@ description: A Flutter plugin for getting information about and controlling the
   and streaming image buffers to dart.
 repository: https://github.com/flutter/plugins/tree/master/packages/camera/camera
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+camera%22
-version: 0.8.1+3
+version: 0.8.1+4
 
 environment:
   sdk: ">=2.12.0 <3.0.0"

packages/video_player/video_player/test/video_player_test.dart

@@ -856,7 +856,16 @@ class FakeEventsChannel {
   }
 
   void _sendMessage(ByteData data) {
-    ServicesBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
-        eventsMethodChannel.name, data, (ByteData? data) {});
+    _ambiguate(ServicesBinding.instance)!
+        .defaultBinaryMessenger
+        .handlePlatformMessage(
+            eventsMethodChannel.name, data, (ByteData? data) {});
   }
 }
+
+/// This allows a value of type T or T? to be treated as a value of type T?.
+///
+/// We use this so that APIs that have become non-nullable can still be used
+/// with `!` and `?` on the stable branch.
+// TODO(ianh): Remove this once we roll stable in late 2021.
+T? _ambiguate<T>(T? value) => value;