Miscellaneous fixes

- Fix login button color (issue material-components#133)
- Restore obscureText on password field (issue material-components#127)
- Fix AccentColorOverride (issue material-components#128, material-components#132)

Author: jdkoren

mdc_100_series/lib/app.dart

@@ -62,8 +62,8 @@ ThemeData _buildShrineTheme() {
     cardColor: kShrineBackgroundWhite,
     textSelectionColor: kShrinePink100,
     errorColor: kShrineErrorRed,
-    buttonTheme: ButtonThemeData(
-      textTheme: ButtonTextTheme.accent,
+    buttonTheme: base.buttonTheme.copyWith(
+      buttonColor: kShrinePink100,
     ),
     primaryIconTheme: base.iconTheme.copyWith(
         color: kShrineBrown900

mdc_100_series/lib/login.dart

@@ -61,6 +61,7 @@ class _LoginPageState extends State<LoginPage> {
                 decoration: InputDecoration(
                   labelText: 'Password',
                 ),
+                obscureText: true,
               ),
             ),
             ButtonBar(
@@ -105,7 +106,10 @@ class AccentColorOverride extends StatelessWidget {
   Widget build(BuildContext context) {
     return Theme(
       child: child,
-      data: Theme.of(context).copyWith(accentColor: color),
+      data: Theme.of(context).copyWith(
+        accentColor: color,
+        brightness: Brightness.dark,
+      ),
     );
   }
 }