[cc] Rename all cc/ filenames to Chromium style

cc/stubs/Extensions3D.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CC_STUBS_EXTENSIONS3D_H_
-#define CC_STUBS_EXTENSIONS3D_H_
-
-#include "third_party/khronos/GLES2/gl2.h"
-#include "third_party/khronos/GLES2/gl2ext.h"
-
-namespace cc {
-
-class Extensions3D {
-public:
-    enum {
-        TEXTURE_RECTANGLE_ARB = GL_TEXTURE_RECTANGLE_ARB,
-        BGRA_EXT = GL_BGRA_EXT,
-        RGBA8_OES = GL_RGBA8_OES,
-    };
-};
-
-}
-
-
-#endif  // CC_STUBS_EXTENSIONS3D_H_
+// Temporary forwarding header
+#include "cc/stubs/extensions_3d.h"