Changed Blimp client to start with white screen before drawing contents

blimp/client/feature/compositor/blimp_compositor_manager.h

Index: blimp/client/feature/compositor/blimp_compositor_manager.h
diff --git a/blimp/client/feature/compositor/blimp_compositor_manager.h b/blimp/client/feature/compositor/blimp_compositor_manager.h
index 9382c0d90ae5424f7bcc6dbd0c4d8149c0113f7b..ed5d677a420a9d7ff9a6cafa0184e5dabce437e7 100644
--- a/blimp/client/feature/compositor/blimp_compositor_manager.h
+++ b/blimp/client/feature/compositor/blimp_compositor_manager.h
@@ -14,6 +14,11 @@
 namespace blimp {
 namespace client {
 
+class BlimpCompositorManagerClient {
+ public:
+  virtual void OnSwapBuffersCompleted() = 0;
+};
+
 // The BlimpCompositorManager manages multiple BlimpCompositor instances, each
 // mapped to a render widget on the engine. The compositor corresponding to
 // the render widget initialized on the engine will be the |active_compositor_|.
@@ -24,7 +29,8 @@ class BlimpCompositorManager
     : public RenderWidgetFeature::RenderWidgetFeatureDelegate,
       public BlimpCompositorClient {
  public:
-  explicit BlimpCompositorManager(RenderWidgetFeature* render_widget_feature);
+  explicit BlimpCompositorManager(RenderWidgetFeature* render_widget_feature,
+                                  BlimpCompositorManagerClient* client);
   ~BlimpCompositorManager() override;
 
   void SetVisible(bool visible);
@@ -61,6 +67,7 @@ class BlimpCompositorManager
       std::unique_ptr<cc::proto::CompositorMessage> message) override;
 
   // BlimpCompositorClient implementation.
+  void DidCompleteSwapBuffers() override;
   cc::LayerTreeSettings* GetLayerTreeSettings() override;
   scoped_refptr<base::SingleThreadTaskRunner>
   GetCompositorTaskRunner() override;
@@ -103,6 +110,7 @@ class BlimpCompositorManager
   // BlimpCompositorManager does not own this and it is expected to outlive this
   // BlimpCompositorManager instance.
   RenderWidgetFeature* render_widget_feature_;
+  BlimpCompositorManagerClient* client_;
 
   DISALLOW_COPY_AND_ASSIGN(BlimpCompositorManager);
 };