Add setInitialRoute on FlutterView. (flutter/engine#3727)

engine/src/flutter/lib/ui/hooks.dart

@@ -40,25 +40,7 @@ void _updateSemanticsEnabled(bool enabled) {
     window.onSemanticsEnabledChanged();
 }
 
-void _handleNavigationMessage(ByteData data) {
-  if (window._defaultRouteName != null)
-    return;
-  try {
-    final dynamic message = _decodeJSON(_decodeUTF8(data));
-    final dynamic method = message['method'];
-    if (method != 'pushRoute')
-      return;
-    final dynamic args = message['args'];
-    window._defaultRouteName = args[0];
-  } catch (e) {
-    // We ignore any exception and just let the message be dispatched as usual.
-  }
-}
-
 void _dispatchPlatformMessage(String name, ByteData data, int responseId) {
-  if (name == 'flutter/navigation')
-    _handleNavigationMessage(data);
-
   if (window.onPlatformMessage != null) {
     window.onPlatformMessage(name, data, (ByteData responseData) {
       window._respondToPlatformMessage(responseId, responseData);

engine/src/flutter/lib/ui/window.dart

@@ -275,8 +275,8 @@ class Window {
 
   /// The route or path that the operating system requested when the application
   /// was launched.
-  String get defaultRouteName => _defaultRouteName;
-  String _defaultRouteName;
+  String get defaultRouteName => _defaultRouteName();
+  String _defaultRouteName() native "Window_defaultRouteName";
 
   /// Requests that, at the next appropriate opportunity, the [onBeginFrame]
   /// and [onDrawFrame] callbacks be invoked.

engine/src/flutter/lib/ui/window/window.cc

@@ -39,6 +39,11 @@ Dart_Handle ToByteData(const std::vector<uint8_t>& buffer) {
   return data_handle;
 }
 
+void DefaultRouteName(Dart_NativeArguments args) {
+  std::string routeName = UIDartState::Current()->window()->client()->DefaultRouteName();
+  Dart_SetReturnValue(args, StdStringToDart(routeName));
+}
+
 void ScheduleFrame(Dart_NativeArguments args) {
   UIDartState::Current()->window()->client()->ScheduleFrame();
 }
@@ -253,6 +258,7 @@ void Window::CompletePlatformMessageResponse(int response_id,
 
 void Window::RegisterNatives(tonic::DartLibraryNatives* natives) {
   natives->Register({
+      {"Window_defaultRouteName", DefaultRouteName, 1, true},
       {"Window_scheduleFrame", ScheduleFrame, 1, true},
       {"Window_sendPlatformMessage", _SendPlatformMessage, 4, true},
       {"Window_respondToPlatformMessage", _RespondToPlatformMessage, 3, true},

engine/src/flutter/lib/ui/window/window.h

@@ -23,6 +23,7 @@ class Scene;
 
 class WindowClient {
  public:
+  virtual std::string DefaultRouteName() = 0;
   virtual void ScheduleFrame() = 0;
   virtual void Render(Scene* scene) = 0;
   virtual void UpdateSemantics(SemanticsUpdate* update) = 0;

engine/src/flutter/runtime/runtime_controller.cc

@@ -98,6 +98,10 @@ Window* RuntimeController::GetWindow() {
   return dart_controller_->dart_state()->window();
 }
 
+std::string RuntimeController::DefaultRouteName() {
+  return client_->DefaultRouteName();
+}
+
 void RuntimeController::ScheduleFrame() {
   client_->ScheduleFrame();
 }

engine/src/flutter/runtime/runtime_controller.h

@@ -52,6 +52,7 @@ class RuntimeController : public WindowClient, public IsolateClient {
 
   Window* GetWindow();
 
+  std::string DefaultRouteName() override;
   void ScheduleFrame() override;
   void Render(Scene* scene) override;
   void UpdateSemantics(SemanticsUpdate* update) override;

engine/src/flutter/runtime/runtime_delegate.h

@@ -17,6 +17,7 @@ namespace blink {
 
 class RuntimeDelegate {
  public:
+  virtual std::string DefaultRouteName() = 0;
   virtual void ScheduleFrame() = 0;
   virtual void Render(std::unique_ptr<flow::LayerTree> layer_tree) = 0;
   virtual void UpdateSemantics(std::vector<SemanticsNode> update) = 0;

engine/src/flutter/shell/common/engine.cc

@@ -310,7 +310,7 @@ void Engine::DispatchPlatformMessage(
     return;
   }
 
-  // If there's no runtime_, we need to buffer some navigation messages.
+  // If there's no runtime_, we may still need to set the initial route.
   if (message->channel() == kNavigationChannel)
     HandleNavigationPlatformMessage(std::move(message));
 }
@@ -341,10 +341,10 @@ bool Engine::HandleNavigationPlatformMessage(
     return false;
   auto root = document.GetObject();
   auto method = root.FindMember("method");
-  if (method == root.MemberEnd() || method->value != "pushRoute")
+  if (method->value != "setInitialRoute")
     return false;
-
-  pending_push_route_message_ = std::move(message);
+  auto route = root.FindMember("args");
+  initial_route_ = std::move(route->value.GetString());
   return true;
 }
 
@@ -427,8 +427,6 @@ void Engine::ConfigureRuntime(const std::string& script_uri) {
   runtime_->SetViewportMetrics(viewport_metrics_);
   runtime_->SetLocale(language_code_, country_code_);
   runtime_->SetSemanticsEnabled(semantics_enabled_);
-  if (pending_push_route_message_)
-    runtime_->DispatchPlatformMessage(std::move(pending_push_route_message_));
 }
 
 void Engine::DidCreateMainIsolate(Dart_Isolate isolate) {
@@ -450,6 +448,13 @@ void Engine::StartAnimatorIfPossible() {
     animator_->Start();
 }
 
+std::string Engine::DefaultRouteName() {
+  if (!initial_route_.empty()) {
+    return initial_route_;
+  }
+  return "/";
+}
+
 void Engine::ScheduleFrame() {
   animator_->RequestFrame();
 }

engine/src/flutter/shell/common/engine.h

@@ -71,6 +71,7 @@ class Engine : public blink::RuntimeDelegate {
 
  private:
   // RuntimeDelegate methods:
+  std::string DefaultRouteName() override;
   void ScheduleFrame() override;
   void Render(std::unique_ptr<flow::LayerTree> layer_tree) override;
   void UpdateSemantics(std::vector<blink::SemanticsNode> update) override;
@@ -98,7 +99,7 @@ class Engine : public blink::RuntimeDelegate {
   std::unique_ptr<Animator> animator_;
   std::unique_ptr<blink::RuntimeController> runtime_;
   tonic::DartErrorHandleType load_script_error_;
-  ftl::RefPtr<blink::PlatformMessage> pending_push_route_message_;
+  std::string initial_route_;
   blink::ViewportMetrics viewport_metrics_;
   std::string language_code_;
   std::string country_code_;

engine/src/flutter/shell/platform/android/io/flutter/view/FlutterView.java

@@ -241,6 +241,10 @@ public class FlutterView extends SurfaceView
         mFlutterSystemChannel.send(message);
     }
 
+    public void setInitialRoute(String route) {
+        mFlutterNavigationChannel.invokeMethod("setInitialRoute", route);
+    }
+
     public void pushRoute(String route) {
         mFlutterNavigationChannel.invokeMethod("pushRoute", route);
     }