Add support for system-level routing

Now you can supply a route argument to flutter start:

  $ flutter start --route /foo

which will start the app at /foo instead of /.

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

@@ -59,7 +59,7 @@ class MaterialApp extends StatefulComponent {
   _MaterialAppState createState() => new _MaterialAppState();
 }
 
-class _MaterialAppState extends State<MaterialApp> {
+class _MaterialAppState extends State<MaterialApp> implements BindingObserver {
 
   GlobalObjectKey _navigator;
 
@@ -68,28 +68,25 @@ class _MaterialAppState extends State<MaterialApp> {
   void initState() {
     super.initState();
     _navigator = new GlobalObjectKey(this);
-    WidgetFlutterBinding.instance.addEventListener(_backHandler);
     _size = ui.window.size;
-    FlutterBinding.instance.addMetricListener(_metricHandler);
+    FlutterBinding.instance.addObserver(this);
   }
 
   void dispose() {
-    WidgetFlutterBinding.instance.removeEventListener(_backHandler);
-    FlutterBinding.instance.removeMetricListener(_metricHandler);
+    FlutterBinding.instance.removeObserver(this);
     super.dispose();
   }
 
-  void _backHandler(InputEvent event) {
+  bool didPopRoute() {
     assert(mounted);
-    if (event.type == 'back') {
     NavigatorState navigator = _navigator.currentState;
     assert(navigator != null);
     if (!navigator.pop())
       activity.finishCurrentActivity();
-    }
+    return true;
   }
 
-  void _metricHandler(Size size) => setState(() { _size = size; });
+  void didChangeSize(Size size) => setState(() { _size = size; });
 
   final HeroController _heroController = new HeroController();
 
@@ -116,6 +113,7 @@ class _MaterialAppState extends State<MaterialApp> {
               title: config.title,
               child: new Navigator(
                 key: _navigator,
+                initialRoute: ui.window.defaultRouteName,
                 onGenerateRoute: _generateRoute,
                 observer: _heroController
               )

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

@@ -132,6 +132,11 @@ class _PointerEventConverter {
   }
 }
 
+class BindingObserver {
+  bool didPopRoute() => false;
+  void didChangeSize(Size size) { }
+}
+
 /// The glue between the render tree and the Flutter engine
 class FlutterBinding extends HitTestTarget {
 
@@ -139,9 +144,9 @@ class FlutterBinding extends HitTestTarget {
     assert(_instance == null);
     _instance = this;
 
-    ui.window.onEvent = _handleEvent;
     ui.window.onPointerPacket = _handlePointerPacket;
     ui.window.onMetricsChanged = _handleMetricsChanged;
+    ui.window.onPopRoute = _handlePopRoute;
 
     if (renderViewOverride == null) {
       _renderView = new RenderView(child: root);
@@ -165,19 +170,16 @@ class FlutterBinding extends HitTestTarget {
   RenderView get renderView => _renderView;
   RenderView _renderView;
 
-  final List<MetricListener> _metricListeners = new List<MetricListener>();
-
-  /// Calls listener for every event that isn't localized to a given view coordinate
-  void addMetricListener(MetricListener listener) => _metricListeners.add(listener);
+  final List<BindingObserver> _observers = new List<BindingObserver>();
 
-  /// Stops calling listener for every event that isn't localized to a given view coordinate
-  bool removeMetricListener(MetricListener listener) => _metricListeners.remove(listener);
+  void addObserver(BindingObserver observer) => _observers.add(observer);
+  bool removeObserver(BindingObserver observer) => _observers.remove(observer);
 
   void _handleMetricsChanged() {
     Size size = ui.window.size;
     _renderView.rootConstraints = new ViewConstraints(size: size);
-    for (MetricListener listener in _metricListeners)
-      listener(size);
+    for (BindingObserver observer in _observers)
+      observer.didChangeSize(size);
   }
 
   void _handlePersistentFrameCallback(Duration timeStamp) {
@@ -192,23 +194,11 @@ class FlutterBinding extends HitTestTarget {
     _renderView.compositeFrame();
   }
 
-  final List<EventListener> _eventListeners = new List<EventListener>();
-
-  /// Calls listener for every event that isn't localized to a given view coordinate
-  void addEventListener(EventListener listener) => _eventListeners.add(listener);
-
-  /// Stops calling listener for every event that isn't localized to a given view coordinate
-  bool removeEventListener(EventListener listener) => _eventListeners.remove(listener);
-
-  // TODO(abarth): The engine should give us the timeStamp in Durations.
-  void _handleEvent(String eventType, double timeStamp) {
-    assert(eventType == 'back');
-    InputEvent ourEvent = new InputEvent(
-      type: eventType,
-      timeStamp: new Duration(microseconds: timeStamp.round())
-    );
-    for (EventListener listener in _eventListeners)
-      listener(ourEvent);
+  void _handlePopRoute() {
+    for (BindingObserver observer in _observers) {
+      if (observer.didPopRoute())
+        return;
+    }
   }
 
   void _handlePointerPacket(ByteData serializedPacket) {

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

@@ -51,6 +51,7 @@ class NavigatorObserver {
 class Navigator extends StatefulComponent {
   Navigator({
     Key key,
+    this.initialRoute,
     this.onGenerateRoute,
     this.onUnknownRoute,
     this.observer
@@ -58,6 +59,7 @@ class Navigator extends StatefulComponent {
     assert(onGenerateRoute != null);
   }
 
+  final String initialRoute;
   final RouteFactory onGenerateRoute;
   final RouteFactory onUnknownRoute;
   final NavigatorObserver observer;
@@ -77,7 +79,9 @@ class NavigatorState extends State<Navigator> {
     super.initState();
     assert(config.observer == null || config.observer.navigator == null);
     config.observer?._navigator = this;
-    push(config.onGenerateRoute(new NamedRouteSettings(name: Navigator.defaultRouteName)));
+    push(config.onGenerateRoute(new NamedRouteSettings(
+      name: config.initialRoute ?? Navigator.defaultRouteName
+    )));
   }
 
   void didUpdateConfig(Navigator oldConfig) {

packages/flutter_tools/lib/src/commands/listen.dart

@@ -59,7 +59,7 @@ class ListenCommand extends FlutterCommand {
             if (package == null || !device.isConnected())
               continue;
             if (device is AndroidDevice) {
-              device.startBundle(package, localBundlePath, true, argResults['checked']);
+              device.startBundle(package, localBundlePath, poke: true, checked: argResults['checked']);
             } else if (device is IOSDevice) {
               device.pushFile(package, localBundlePath, _remoteFlutterBundle);
             } else if (device is IOSSimulator) {

packages/flutter_tools/lib/src/commands/start.dart

@@ -33,6 +33,7 @@ class StartCommand extends FlutterCommand {
         defaultsTo: '',
         abbr: 't',
         help: 'Target app path or filename to start.');
+    argParser.addOption('route', help: 'Which route to load when starting the app.');
     argParser.addFlag('boot',
         help: 'Boot the iOS Simulator if it isn\'t already running.');
   }
@@ -88,7 +89,10 @@ class StartCommand extends FlutterCommand {
         await builder.buildInTempDir(
           mainPath: mainPath,
           onBundleAvailable: (String localBundlePath) {
-            if (device.startBundle(package, localBundlePath, poke, argResults['checked']))
+            if (device.startBundle(package, localBundlePath,
+                                   poke: poke,
+                                   checked: argResults['checked'],
+                                   route: argResults['route']))
               startedSomething = true;
           }
         );

packages/flutter_tools/lib/src/device.dart

@@ -768,7 +768,11 @@ class AndroidDevice extends Device {
     runCheckedSync(adbCommandForDevice(['forward', portString, portString]));
   }
 
-  bool startBundle(AndroidApk apk, String bundlePath, bool poke, bool checked) {
+  bool startBundle(AndroidApk apk, String bundlePath, {
+    bool poke,
+    bool checked,
+    String route
+  }) {
     if (!FileSystemEntity.isFileSync(bundlePath)) {
       _logging.severe('Cannot find $bundlePath');
       return false;
@@ -786,6 +790,8 @@ class AndroidDevice extends Device {
     ]);
     if (checked)
       cmd.addAll(['--ez', 'enable-checked-mode', 'true']);
+    if (route != null)
+      cmd.addAll(['--es', 'route', route]);
     cmd.add(apk.launchActivity);
     runCheckedSync(cmd);
     return true;

packages/flutter_tools/test/start_test.dart

@@ -21,7 +21,7 @@ defineTests() {
       when(mockDevices.android.isConnected()).thenReturn(true);
       when(mockDevices.android.isAppInstalled(any)).thenReturn(false);
       when(mockDevices.android.installApp(any)).thenReturn(true);
-      when(mockDevices.android.startBundle(any, any, any, any)).thenReturn(true);
+      when(mockDevices.android.startBundle(any, any)).thenReturn(true);
       when(mockDevices.android.stopApp(any)).thenReturn(true);
 
       when(mockDevices.iOS.isConnected()).thenReturn(false);
@@ -49,7 +49,7 @@ defineTests() {
       when(mockDevices.android.isConnected()).thenReturn(false);
       when(mockDevices.android.isAppInstalled(any)).thenReturn(false);
       when(mockDevices.android.installApp(any)).thenReturn(false);
-      when(mockDevices.android.startBundle(any, any, any, any)).thenReturn(false);
+      when(mockDevices.android.startBundle(any, any)).thenReturn(false);
       when(mockDevices.android.stopApp(any)).thenReturn(false);
 
       when(mockDevices.iOS.isConnected()).thenReturn(true);