aura: Remove CreateOffscreenContext from ui::ContextFactory.

ui/compositor/context_provider_from_context_factory.h

-// Copyright (c) 2013 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 UI_COMPOSITOR_CONTEXT_PROVIDER_FROM_CONTEXT_FACTORY_H_
-#define UI_COMPOSITOR_CONTEXT_PROVIDER_FROM_CONTEXT_FACTORY_H_
-
-#include "base/synchronization/lock.h"
-#include "cc/output/context_provider.h"
-#include "third_party/WebKit/public/platform/WebGraphicsContext3D.h"
-#include "ui/compositor/compositor.h"
-#include "webkit/common/gpu/grcontext_for_webgraphicscontext3d.h"
-
-namespace ui {
-
-class ContextProviderFromContextFactory
-    : public cc::ContextProvider {
- public:
-  static scoped_refptr<ContextProviderFromContextFactory> CreateForOffscreen(
-      ContextFactory* factory);
-
-  virtual bool BindToCurrentThread() OVERRIDE;
-  virtual WebKit::WebGraphicsContext3D* Context3d() OVERRIDE;
-  virtual class GrContext* GrContext() OVERRIDE;
-  virtual void VerifyContexts() OVERRIDE;
-  virtual bool DestroyedOnMainThread() OVERRIDE;
-  virtual void SetLostContextCallback(const LostContextCallback& cb) OVERRIDE;
-
- protected:
-  ContextProviderFromContextFactory(ContextFactory* factory);
-  virtual ~ContextProviderFromContextFactory();
-
-  bool InitializeOnMainThread();
-
- private:
-  ContextFactory* factory_;
-  base::Lock destroyed_lock_;
-  bool destroyed_;
-  scoped_ptr<WebKit::WebGraphicsContext3D> context3d_;
-  scoped_ptr<webkit::gpu::GrContextForWebGraphicsContext3D> gr_context_;
-};
-
-}  // namespace ui
-
-#endif  // UI_COMPOSITOR_CONTEXT_PROVIDER_FROM_CONTEXT_FACTORY_H_