Change Canvas2DLayerBridge to stay alive until last mailbox is returned.

Source/core/platform/graphics/chromium/Canvas2DLayerManagerTest.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 34 matching lines @@
 class FakeCanvas2DLayerBridge : public Canvas2DLayerBridge {
 public:
     FakeCanvas2DLayerBridge(PassRefPtr<GraphicsContext3D> context, SkDeferredCanvas* canvas)
         : Canvas2DLayerBridge(context, canvas, NonOpaque)
         , m_freeableBytes(0)
         , m_freeMemoryIfPossibleCount(0)
         , m_flushCount(0)
     {
     }
 
+    ~FakeCanvas2DLayerBridge()
+    {
+        m_destructionInProgress = true;
+    }
+
     virtual size_t storageAllocatedForRecording() OVERRIDE
     {
         // Because the fake layer has no canvas to query, just
         // return status quo. Allocation changes that would normally be
         // initiated by the canvas can be faked by invoking
         // storageAllocatedForRecordingChanged directly from the test code.
         return m_bytesAllocated;
     }
 
     void fakeFreeableBytes(size_t size)
@@ skipping 189 matching lines @@
     flushEvictionTest();
 }
 
 TEST_F(Canvas2DLayerManagerTest, testDeferredFrame)
 {
     deferredFrameTest();
 }
 
 } // namespace