Reland of cc: Add mailbox support to ResourceProvider write locks.

cc/tiles/tile_task_manager.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 CC_TILES_TILE_TASK_MANAGER_H_
 #define CC_TILES_TILE_TASK_MANAGER_H_
 
 #include <stddef.h>
 
 #include "cc/raster/raster_buffer_provider.h"
@@ skipping 14 matching lines @@
   // Previously scheduled tasks that are not in |graph| will be canceled unless
   // already running. Once scheduled and if not canceled by next scheduling,
   // tasks are guaranteed to run.
   virtual void ScheduleTasks(TaskGraph* graph) = 0;
 
   // Check for completed tasks and call OnTaskCompleted() on them.
   virtual void CheckForCompletedTasks() = 0;
 
   // Shutdown after canceling all previously scheduled tasks.
   virtual void Shutdown() = 0;
-
-  // Get RasterBufferProvider.
-  virtual RasterBufferProvider* GetRasterBufferProvider() const = 0;
 };
 
 class CC_EXPORT TileTaskManagerImpl : public TileTaskManager {
  public:
   ~TileTaskManagerImpl() override;
 
   static std::unique_ptr<TileTaskManagerImpl> Create(
-      std::unique_ptr<RasterBufferProvider> raster_buffer_provider,
       TaskGraphRunner* task_graph_runner);
 
   // Overridden from TileTaskManager:
   void ScheduleTasks(TaskGraph* graph) override;
   void CheckForCompletedTasks() override;
   void Shutdown() override;
-  RasterBufferProvider* GetRasterBufferProvider() const override;
 
  protected:
-  TileTaskManagerImpl(
-      std::unique_ptr<RasterBufferProvider> raster_buffer_provider,
-      TaskGraphRunner* task_graph_runner);
+  explicit TileTaskManagerImpl(TaskGraphRunner* task_graph_runner);
 
-  std::unique_ptr<RasterBufferProvider> raster_buffer_provider_;
   TaskGraphRunner* task_graph_runner_;
   const NamespaceToken namespace_token_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TileTaskManagerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_TILE_TASK_MANAGER_H_