Route D3D VSync signal to Compositor

content/browser/compositor/gpu_vsync_begin_frame_source.h

+// Copyright 2016 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_COMPOSITOR_GPU_VSYNC_BEGIN_FRAME_SOURCE_H_
+#define CONTENT_BROWSER_COMPOSITOR_GPU_VSYNC_BEGIN_FRAME_SOURCE_H_
+
+#include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
+#include "cc/scheduler/begin_frame_source.h"
+
+namespace content {
+
+// This class is used to control VSync production on GPU side.
+class GpuVSyncControl {
+ public:
+  virtual void SetNeedsVSync(bool needs_vsync) = 0;
+};
+
+// This is a type of ExternalBeginFrameSource where VSync signals are
+// generated externally on GPU side.
+class GpuVSyncBeginFrameSource : public cc::ExternalBeginFrameSource,
+                                 cc::ExternalBeginFrameSourceClient {
+ public:
+  explicit GpuVSyncBeginFrameSource(GpuVSyncControl* vsync_control);
+  ~GpuVSyncBeginFrameSource() override;
+
+  // cc::ExternalBeginFrameSourceClient implementation.
+  void OnNeedsBeginFrames(bool needs_begin_frames) override;
+  void OnDidFinishFrame(const cc::BeginFrameAck& ack) override;
+
+  void OnVSync(base::TimeTicks timestamp, base::TimeDelta interval);
+
+ private:
+  GpuVSyncControl* const vsync_control_;
+  bool needs_begin_frames_;
+  uint64_t next_sequence_number_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuVSyncBeginFrameSource);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_COMPOSITOR_GPU_VSYNC_BEGIN_FRAME_SOURCE_H_