cc: Emulate BeginFrame in OutputSurfaces that don't support it natively

cc/scheduler/vsync_time_source.h

-// Copyright 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_SCHEDULER_VSYNC_TIME_SOURCE_H_
-#define CC_SCHEDULER_VSYNC_TIME_SOURCE_H_
-
-#include "cc/base/cc_export.h"
-#include "cc/scheduler/time_source.h"
-
-namespace cc {
-
-class CC_EXPORT VSyncClient {
- public:
-  virtual void DidVSync(base::TimeTicks frame_time) = 0;
-
- protected:
-  virtual ~VSyncClient() {}
-};
-
-class VSyncProvider {
- public:
-  // Request to be notified of future vsync events. The notifications will be
-  // delivered until they are disabled by calling this function with a null
-  // client.
-  virtual void RequestVSyncNotification(VSyncClient* client) = 0;
-
- protected:
-  virtual ~VSyncProvider() {}
-};
-
-// This timer implements a time source that is explicitly triggered by an
-// external vsync signal.
-class CC_EXPORT VSyncTimeSource : public TimeSource, public VSyncClient {
- public:
-  enum NotificationDisableOption {
-    // The notification will be lazily disabled in the callback to ensure
-    // we get notified of the frame immediately following a quick on-off-on
-    // transition.
-    DISABLE_ON_NEXT_TICK,
-    DISABLE_SYNCHRONOUSLY
-  };
-
-  static scoped_refptr<VSyncTimeSource> Create(
-      VSyncProvider* vsync_provider, NotificationDisableOption option);
-
-  // TimeSource implementation
-  virtual void SetClient(TimeSourceClient* client) OVERRIDE;
-  virtual void SetTimebaseAndInterval(base::TimeTicks timebase,
-                                      base::TimeDelta interval) OVERRIDE;
-  virtual void SetActive(bool active) OVERRIDE;
-  virtual bool Active() const OVERRIDE;
-  virtual base::TimeTicks LastTickTime() OVERRIDE;
-  virtual base::TimeTicks NextTickTime() OVERRIDE;
-
-  // VSyncClient implementation
-  virtual void DidVSync(base::TimeTicks frame_time) OVERRIDE;
-
- protected:
-  explicit VSyncTimeSource(VSyncProvider* vsync_provider,
-                           NotificationDisableOption option);
-  virtual ~VSyncTimeSource();
-
-  base::TimeTicks last_tick_time_;
-  base::TimeDelta interval_;
-  bool active_;
-  bool notification_requested_;
-
-  VSyncProvider* vsync_provider_;
-  TimeSourceClient* client_;
-  NotificationDisableOption disable_option_;
-
-  DISALLOW_COPY_AND_ASSIGN(VSyncTimeSource);
-};
-
-}  // namespace cc
-
-#endif  // CC_SCHEDULER_VSYNC_TIME_SOURCE_H_