cc: Add mailbox support to ResourceProvider write locks.

cc/test/fake_raster_buffer_provider.h

Index: cc/test/fake_raster_buffer_provider.h
diff --git a/cc/test/fake_raster_buffer_provider.h b/cc/test/fake_raster_buffer_provider.h
index 00ab04a619577f66f40aa1dca663193e8bb61ab1..4573f983a487b1f5ba2600df061d271a08a5a488 100644
--- a/cc/test/fake_raster_buffer_provider.h
+++ b/cc/test/fake_raster_buffer_provider.h
@@ -21,7 +21,7 @@ class FakeRasterBufferProviderImpl : public RasterBufferProvider {
       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;