Free temporary GPU and memory resources held by inactive or hidden 2D canvases

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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.
@@ skipping 418 matching lines @@
 {
     OpacityMode opacityMode = !m_context || m_context->hasAlpha() ? NonOpaque : Opaque;
 
     *msaaSampleCount = 0;
     if (is3D())
         return adoptPtr(new WebGLImageBufferSurface(size(), opacityMode));
 
     if (shouldAccelerate(deviceSize)) {
         if (document().settings())
             *msaaSampleCount = document().settings()->accelerated2dCanvasMSAASampleCount();
-        OwnPtr<ImageBufferSurface> surface = adoptPtr(new Canvas2DImageBufferSurface(size(), opacityMode, *msaaSampleCount));
+        OwnPtr<ImageBufferSurface> surface = adoptPtr(new Canvas2DImageBufferSurface(this, size(), opacityMode, *msaaSampleCount));
         if (surface->isValid())
             return surface.release();
     }
 
     return adoptPtr(new UnacceleratedImageBufferSurface(size(), opacityMode));
 }
 
 void HTMLCanvasElement::createImageBuffer()
 {
     ASSERT(!m_imageBuffer);
@@ skipping 104 matching lines @@
     m_didClearImageBuffer = false;
 }
 
 AffineTransform HTMLCanvasElement::baseTransform() const
 {
     ASSERT(hasImageBuffer() && !m_didFailToCreateImageBuffer);
     return m_imageBuffer->baseTransform();
 }
 
 }