cc: Use correct message loop proxy in BlockingTaskRunner

cc/trees/proxy.h

 // Copyright 2011 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_TREES_PROXY_H_
 #define CC_TREES_PROXY_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 12 matching lines @@
 class SingleThreadTaskRunner;
 }
 
 namespace gfx {
 class Rect;
 class Vector2d;
 }
 
 namespace cc {
 
+class BlockingTaskRunner;
 class LayerTreeDebugState;
 class OutputSurface;
 struct RendererCapabilities;
 
 // Abstract class responsible for proxying commands from the main-thread side of
 // the compositor over to the compositor implementation.
 class CC_EXPORT Proxy {
  public:
   base::SingleThreadTaskRunner* MainThreadTaskRunner() const;
   bool HasImplThread() const;
@@ skipping 63 matching lines @@
  protected:
   Proxy(scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
         scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner);
   friend class DebugScopedSetImplThread;
   friend class DebugScopedSetMainThread;
   friend class DebugScopedSetMainThreadBlocked;
 
  private:
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner_;
+
+  // Blocking task runner which forwards tasks to |main_task_runner_| while the
+  // Proxy is alive.
+  scoped_refptr<BlockingTaskRunner> blocking_main_thread_task_runner_;
+
 #if DCHECK_IS_ON
   const base::PlatformThreadId main_thread_id_;
   bool impl_thread_is_overridden_;
   bool is_main_thread_blocked_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(Proxy);
 };
 
 #if DCHECK_IS_ON
@@ skipping 17 matching lines @@
   explicit DebugScopedSetMainThreadBlocked(Proxy* proxy) {}
   ~DebugScopedSetMainThreadBlocked() {}
  private:
   DISALLOW_COPY_AND_ASSIGN(DebugScopedSetMainThreadBlocked);
 };
 #endif
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROXY_H_