Cleanup: Move ContextProviderWebContext into cc/blink.

webkit/common/gpu/context_provider_web_context.h

-// Copyright 2014 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 WEBKIT_COMMON_GPU_CONTEXT_PROVIDER_WEB_CONTEXT_H_
-#define WEBKIT_COMMON_GPU_CONTEXT_PROVIDER_WEB_CONTEXT_H_
-
-#include "cc/output/context_provider.h"
-
-namespace blink { class WebGraphicsContext3D; }
-
-namespace webkit {
-namespace gpu {
-
-class ContextProviderWebContext : public cc::ContextProvider {
- public:
-  virtual blink::WebGraphicsContext3D* WebContext3D() = 0;
-
- protected:
-  ~ContextProviderWebContext() override {}
-};
-
-}  // namespace gpu
-}  // namespace webkit
-
-#endif  // WEBKIT_COMMON_GPU_CONTEXT_PROVIDER_WEB_CONTEXT_H_