Make lost context callback a base::Closure thru the WGC3DProvider.

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h

 /*
  * Copyright (C) 2009 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 507 matching lines @@
     HeapHashSet<WeakMember<WebGLContextObject>> m_contextObjects;
 #else
     // The hash set isn't traced, hence the references are effectively
     // weakly kept. Each WebGLContextObject is responsible for detaching
     // itself upon finalization if the WebGLRenderingContextBase hasn't been
     // finalized already and detached them via detachAndRemoveAllObjects().
     // See http://crbug.com/534524 for the details.
     HashSet<UntracedMember<WebGLContextObject>> m_contextObjects;
 #endif
 
-    PersistentWillBeMember<WebGLRenderingContextLostCallback> m_contextLostCallbackAdapter;
     PersistentWillBeMember<WebGLRenderingContextErrorMessageCallback> m_errorMessageCallbackAdapter;
 
     // List of bound VBO's. Used to maintain info about sizes for ARRAY_BUFFER and stored values for ELEMENT_ARRAY_BUFFER
     PersistentWillBeMember<WebGLBuffer> m_boundArrayBuffer;
 
     PersistentWillBeMember<WebGLVertexArrayObjectBase> m_defaultVertexArrayObject;
     PersistentWillBeMember<WebGLVertexArrayObjectBase> m_boundVertexArrayObject;
     bool m_preservedDefaultVAOObjectWrapper;
     void setBoundVertexArrayObject(ScriptState*, WebGLVertexArrayObjectBase*);
 
@@ skipping 565 matching lines @@
 #endif
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase, CanvasRenderingContext, context, context->is3d(), context.is3d());
 
 } // namespace blink
 
 WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(blink::WebGLRenderingContextBase::TextureUnitState);
 
 #endif // WebGLRenderingContextBase_h