Support application lifecycle state change events in the framework

packages/flutter/lib/src/material/material_app.dart

@@ -104,6 +104,8 @@ class _MaterialAppState extends State<MaterialApp> implements BindingObserver {
     }
   }
 
+  void didChangeAppLifecycleState(ui.AppLifecycleState state) { }
+
   final HeroController _heroController = new HeroController();
 
   Route _generateRoute(RouteSettings settings) {

packages/flutter/lib/src/widgets/binding.dart

@@ -16,6 +16,7 @@ class BindingObserver {
   bool didPopRoute() => false;
   void didChangeSize(Size size) { }
   void didChangeLocale(ui.Locale locale) { }
+  void didChangeAppLifecycleState(ui.AppLifecycleState state) { }
 }
 
 /// A concrete binding for applications based on the Widgets framework.
@@ -39,6 +40,7 @@ class WidgetFlutterBinding extends BindingBase with Scheduler, Gesturer, Rendere
     BuildableElement.scheduleBuildFor = scheduleBuildFor;
     ui.window.onLocaleChanged = handleLocaleChanged;
     ui.window.onPopRoute = handlePopRoute;
+    ui.window.onAppLifecycleStateChanged = handleAppLifecycleStateChanged;
   }
 
   /// The one static instance of this class.
@@ -79,6 +81,11 @@ class WidgetFlutterBinding extends BindingBase with Scheduler, Gesturer, Rendere
     }
   }
 
+  void handleAppLifecycleStateChanged(ui.AppLifecycleState state) {
+    for (BindingObserver observer in _observers)
+      observer.didChangeAppLifecycleState(state);
+  }
+
   void beginFrame() {
     buildDirtyElements();
     super.beginFrame();

packages/flutter/pubspec.yaml

@@ -8,8 +8,8 @@ dependencies:
   collection: '>=1.1.3 <2.0.0'
   intl: '>=0.12.4+2 <0.13.0'
   material_design_icons: '>=0.0.3 <0.1.0'
-  sky_engine: 0.0.73
-  sky_services: 0.0.73
+  sky_engine: 0.0.74
+  sky_services: 0.0.74
   vector_math: '>=1.4.3 <2.0.0'
 
   # See the comment in flutter_tools' pubspec.yaml. We have to pin it