Set content opacity of DFHAndroid surfacelayer based on renderer frame contents.

ui/android/delegated_frame_host_android.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_ANDROID_DELEGATED_FRAME_HOST_ANDROID_H_
 #define UI_ANDROID_DELEGATED_FRAME_HOST_ANDROID_H_
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "cc/output/copy_output_request.h"
@@ skipping 44 matching lines @@
   // Should only be called when the host has a content layer.
   void RequestCopyOfSurface(
       WindowAndroidCompositor* compositor,
       const gfx::Rect& src_subrect_in_pixel,
       cc::CopyOutputRequest::CopyOutputRequestCallback result_callback);
 
   void OutputSurfaceChanged();
 
   void UpdateBackgroundColor(SkColor color);
 
-  void SetContentsOpaque(bool opaque);
-
   void UpdateContainerSizeinDIP(const gfx::Size& size_in_dip);
 
  private:
   // cc::SurfaceFactoryClient implementation.
   void ReturnResources(const cc::ReturnedResourceArray& resources) override;
   void SetBeginFrameSource(cc::BeginFrameSource* begin_frame_source) override;
 
   void UpdateBackgroundLayer();
 
   ViewAndroid* view_;
 
   cc::SurfaceManager* surface_manager_;
   std::unique_ptr<cc::SurfaceIdAllocator> surface_id_allocator_;
   ReturnResourcesCallback return_resources_callback_;
 
   std::unique_ptr<cc::SurfaceFactory> surface_factory_;
 
   struct FrameData {
     FrameData();
     ~FrameData();
 
     cc::SurfaceId surface_id;
     gfx::Size surface_size;
     float top_controls_height;
     float top_controls_shown_ratio;
     float bottom_controls_height;
     float bottom_controls_shown_ratio;
     cc::Selection<gfx::SelectionBound> viewport_selection;
+    bool has_transparent_background;
   };
   std::unique_ptr<FrameData> current_frame_;
 
   scoped_refptr<cc::SurfaceLayer> content_layer_;
 
   scoped_refptr<cc::Layer> background_layer_;
 
   gfx::Size container_size_in_dip_;
 
   DISALLOW_COPY_AND_ASSIGN(DelegatedFrameHostAndroid);
 };
 
 }  // namespace ui
 
 #endif  // UI_ANDROID_DELEGATED_FRAME_HOST_ANDROID_H_