cc: Add mailbox support to ResourceProvider write locks.

cc/test/fake_tile_task_manager.h

Index: cc/test/fake_tile_task_manager.h
diff --git a/cc/test/fake_tile_task_manager.h b/cc/test/fake_tile_task_manager.h
index b6ee2cf34a787a2d22aa62e91dfa2c069fac3f19..9c97ca06204ee180546f8793e441828c985dd7ba 100644
--- a/cc/test/fake_tile_task_manager.h
+++ b/cc/test/fake_tile_task_manager.h
@@ -15,19 +15,14 @@ namespace cc {
 class FakeTileTaskManagerImpl : public TileTaskManager {
  public:
   FakeTileTaskManagerImpl();
-  // Ctor for custom raster buffer provider.
-  FakeTileTaskManagerImpl(
-      std::unique_ptr<RasterBufferProvider> raster_buffer_provider);
   ~FakeTileTaskManagerImpl() override;
 
   // Overridden from TileTaskManager:
   void ScheduleTasks(TaskGraph* graph) override;
   void CheckForCompletedTasks() override;
   void Shutdown() override;
-  RasterBufferProvider* GetRasterBufferProvider() const override;
 
  protected:
-  std::unique_ptr<RasterBufferProvider> raster_buffer_provider_;
   Task::Vector completed_tasks_;
 };