Add BeginFrameObserverProxy

content/browser/renderer_host/compositor_begin_frame_observer_impl.h

+// Copyright 2015 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 CONTENT_BROWSER_RENDERER_HOST_COMPOSITOR_BEGIN_FRAME_OBSERVER_IMPL_H_
+#define CONTENT_BROWSER_RENDERER_HOST_COMPOSITOR_BEGIN_FRAME_OBSERVER_IMPL_H_
+
+#include "content/common/content_export.h"
+#include "ui/compositor/compositor.h"
+#include "ui/compositor/compositor_observer.h"
+
+namespace cc {
+struct BeginFrameArgs;
+}
+
+namespace content {
+
+// This is the interface from the CompositorBeginFrameObserverImpl which manages
+// sending BeginFrame messages.
+class CompositorBeginFrameObserverImplClient {
+ public:
+  virtual void SendBeginFrame(const cc::BeginFrameArgs& args) = 0;
+};
+
+// This class is used to manage all of the RenderWidgetHostView state and
+// functionality that is associated with BeginFrame message handling.
+class CONTENT_EXPORT CompositorBeginFrameObserverImpl
+    : public ui::CompositorBeginFrameObserver {
+ public:
+  explicit CompositorBeginFrameObserverImpl(
+      CompositorBeginFrameObserverImplClient* client);
+  virtual ~CompositorBeginFrameObserverImpl();
+
+  void SetNeedsBeginFrames(bool needs_begin_frames);
+
+  void SetCompositor(ui::Compositor* compositor);
+  void ResetCompositor();
+
+  // Overridden from ui::CompositorBeginFrameObserver:
+  void OnSendBeginFrame(const cc::BeginFrameArgs& args) override;
+
+ private:
+  void StartObservingBeginFrames();
+  void StopObservingBeginFrames();
+
+  // True when RenderWidget needs a BeginFrame message.
+  bool needs_begin_frames_;
+
+  // Pass |last_sent_begin_frame_args_| to compositor when |this| is added as a

[danakj, 2015/03/20 16:46:11]

Update this comment?

[simonhong, 2015/03/20 17:24:14]

Done.

+  // CompositorBeginFrameObserver. With this, Compositor can determine whether
+  // latest BeginFrameArgs it has sent can be used immediately or not.
+  cc::BeginFrameArgs last_sent_begin_frame_args_;
+
+  CompositorBeginFrameObserverImplClient* client_;
+  ui::Compositor* compositor_;
+
+  DISALLOW_COPY_AND_ASSIGN(CompositorBeginFrameObserverImpl);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_COMPOSITOR_BEGIN_FRAME_OBSERVER_IMPL_H_