Implement WEBGL_shared_resources

Source/core/html/canvas/WebGLObject.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 38 matching lines @@
     void deleteObject(GraphicsContext3D*);
 
     void onAttached() { ++m_attachmentCount; }
     void onDetached(GraphicsContext3D*);
 
     // This indicates whether the client side issue a delete call already, not
     // whether the OpenGL resource is deleted.
     // object()==0 indicates the OpenGL resource is deleted.
     bool isDeleted() { return m_deleted; }
 
-    // True if this object belongs to the group or context.
-    virtual bool validate(const WebGLContextGroup*, const WebGLRenderingContext*) const = 0;
-
 protected:
     WebGLObject(WebGLRenderingContext*);
 
     // setObject should be only called once right after creating a WebGLObject.
     void setObject(Platform3DObject);
 
     // deleteObjectImpl should be only called once to delete the OpenGL resource.
     virtual void deleteObjectImpl(GraphicsContext3D*, Platform3DObject) = 0;
 
     virtual bool hasGroupOrContext() const = 0;
 
     virtual void detach();
 
+    // Warning!!!: This can only be used on object delete. Using it for
+    // other purposes will mess up shared resources because the changes
+    // will take place on the wrong context.
     virtual GraphicsContext3D* getAGraphicsContext3D() const = 0;
 
 private:
     Platform3DObject m_object;
     unsigned m_attachmentCount;
     bool m_deleted;
 };
 
 } // namespace WebCore
 
 #endif // WebGLObject_h