Re-land "WebGL: Transfer ownership of WebGraphicsContext3D to DrawingBuffer"

Source/core/html/canvas/WebGLContextGroup.cpp

 /*
  * Copyright (C) 2011 Apple 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 32 matching lines @@
 
 WebGLContextGroup::~WebGLContextGroup()
 {
     detachAndRemoveAllObjects();
 }
 
 blink::WebGraphicsContext3D* WebGLContextGroup::getAWebGraphicsContext3D()
 {
     ASSERT(!m_contexts.isEmpty());
     HashSet<WebGLRenderingContextBase*>::iterator it = m_contexts.begin();
-    return (*it)->webGraphicsContext3D();
+    return (*it)->webContext();
 }
 
 void WebGLContextGroup::addContext(WebGLRenderingContextBase* context)
 {
     m_contexts.add(context);
 }
 
 void WebGLContextGroup::removeContext(WebGLRenderingContextBase* context)
 {
     // We must call detachAndRemoveAllObjects before removing the last context.
@@ skipping 25 matching lines @@
 {
     // Detach must happen before loseContextImpl, which destroys the GraphicsContext3D
     // and prevents groupObjects from being properly deleted.
     detachAndRemoveAllObjects();
 
     for (HashSet<WebGLRenderingContextBase*>::iterator it = m_contexts.begin(); it != m_contexts.end(); ++it)
         (*it)->loseContextImpl(mode);
 }
 
 } // namespace WebCore