Revert of 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 9c97ca06204ee180546f8793e441828c985dd7ba..b6ee2cf34a787a2d22aa62e91dfa2c069fac3f19 100644
--- a/cc/test/fake_tile_task_manager.h
+++ b/cc/test/fake_tile_task_manager.h
@@ -15,14 +15,19 @@
 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_;
 };