cc: Route offscreen context creation for compositor to the browser.

cc/context_provider.h

Index: cc/context_provider.h
diff --git a/cc/context_provider.h b/cc/context_provider.h
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+++ b/cc/context_provider.h
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+// 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 CC_CONTEXT_PROVIDER_H_
+#define CC_CONTEXT_PROVIDER_H_
+
+#include "base/memory/ref_counted.h"
+
+class GrContext;
+namespace WebKit { class WebGraphicsContext3D; }
+
+namespace cc {
+
+class ContextProvider : public base::RefCountedThreadSafe<ContextProvider> {
+ public:
+  // Initialize and create a 3d context. This must be called from the main
+  // thread. Calling it more than once should have no effect.
+  virtual bool InitializeOnMainThread() = 0;
+
+  // Bind the 3d context to the current thread. This should be called before
+  // accessing the contexts. Calling it more than once should have no effect.
+  // Once this function has been called, the class should only be accessed
+  // from the same thread.
+  virtual bool BindToCurrentThread() = 0;
+
+  virtual WebKit::WebGraphicsContext3D* Context3d() = 0;
+  virtual class GrContext* GrContext() = 0;
+
+  // Ask the provider to check if the contexts are valid or lost. If they are,
+  // this should invalidate the provider so that it can be replaced with a new
+  // one.
+  virtual void VerifyContexts() = 0;
+
+ protected:
+  friend class base::RefCountedThreadSafe<ContextProvider>;
+  virtual ~ContextProvider() {}
+};
+
+}  // namespace cc
+
+#endif  // CC_CONTEXT_PROVIDER_H_