cc: Add mailbox support to ResourceProvider write locks.

cc/test/fake_raster_buffer_provider.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_TEST_FAKE_RASTER_BUFFER_PROVIDER_H_
 #define CC_TEST_FAKE_RASTER_BUFFER_PROVIDER_H_
 
 #include "cc/raster/raster_buffer_provider.h"
 
 namespace cc {
 
 // Fake RasterBufferProvider that just no-ops all calls.
 class FakeRasterBufferProviderImpl : public RasterBufferProvider {
  public:
   FakeRasterBufferProviderImpl();
   ~FakeRasterBufferProviderImpl() override;
 
   // RasterBufferProvider methods.
   std::unique_ptr<RasterBuffer> AcquireBufferForRaster(
       const Resource* resource,
       uint64_t resource_content_id,
       uint64_t previous_content_id) override;
   void ReleaseBufferForRaster(std::unique_ptr<RasterBuffer> buffer) override;
-  void OrderingBarrier() override;
+  bool OrderingBarrier() override;
   ResourceFormat GetResourceFormat(bool must_support_alpha) const override;
   bool GetResourceRequiresSwizzle(bool must_support_alpha) const override;
   void Shutdown() override;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_FAKE_RASTER_BUFFER_PROVIDER_H_