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

cc/scheduler/frame_rate_controller.h

 // Copyright 2011 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_FRAME_RATE_CONTROLLER_H_
 #define CC_SCHEDULER_FRAME_RATE_CONTROLLER_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time.h"
 #include "cc/base/cc_export.h"
 
 namespace cc {
 
 class Thread;
 class TimeSource;
+class FrameRateController;
 
 class CC_EXPORT FrameRateControllerClient {
+ protected:
+  virtual ~FrameRateControllerClient() {}
+
  public:
   // Throttled is true when we have a maximum number of frames pending.
-  virtual void BeginFrame(bool throttled) = 0;
-
- protected:
-  virtual ~FrameRateControllerClient() {}
+  virtual void FrameRateControllerTick(bool throttled) = 0;
 };
 
 class FrameRateControllerTimeSourceAdapter;
 
+// The FrameRateController is used in cases where we self-tick (i.e. BeginFrame
+// is not sent by a parent compositor.
 class CC_EXPORT FrameRateController {
  public:
   enum {
     DEFAULT_MAX_FRAMES_PENDING = 2
   };
 
   explicit FrameRateController(scoped_refptr<TimeSource> timer);
   // Alternate form of FrameRateController with unthrottled frame-rate.
   explicit FrameRateController(Thread* thread);
   virtual ~FrameRateController();
 
   void SetClient(FrameRateControllerClient* client) { client_ = client; }
 
   void SetActive(bool active);
+  bool IsActive() { return active_; }
 
   // Use the following methods to adjust target frame rate.
   //
   // Multiple frames can be in-progress, but for every DidSwapBuffers, a
   // DidFinishFrame should be posted.
   //
   // If the rendering pipeline crashes, call DidAbortAllPendingFrames.
   void DidSwapBuffers();
   void DidSwapBuffersComplete();
   void DidAbortAllPendingFrames();
-  void SetMaxFramesPending(int max_frames_pending);  // 0 for unlimited.
-  int MaxFramesPending() const { return max_frames_pending_; }
-  int NumFramesPendingForTesting() const { return num_frames_pending_; }
+  void SetMaxSwapsPending(int max_swaps_pending);  // 0 for unlimited.
+  int MaxSwapsPending() const { return max_swaps_pending_; }
+  int NumSwapsPendingForTesting() const { return num_frames_pending_; }
 
   // This returns null for unthrottled frame-rate.
   base::TimeTicks NextTickTime();
 
   // This returns now for unthrottled frame-rate.
   base::TimeTicks LastTickTime();
 
   void SetTimebaseAndInterval(base::TimeTicks timebase,
                               base::TimeDelta interval);
 
  protected:
   friend class FrameRateControllerTimeSourceAdapter;
   void OnTimerTick();
 
   void PostManualTick();
   void ManualTick();
 
   FrameRateControllerClient* client_;
   int num_frames_pending_;
-  int max_frames_pending_;
+  int max_swaps_pending_;
   scoped_refptr<TimeSource> time_source_;
   scoped_ptr<FrameRateControllerTimeSourceAdapter> time_source_client_adapter_;
   bool active_;
 
   // Members for unthrottled frame-rate.
   bool is_time_source_throttling_;
   base::WeakPtrFactory<FrameRateController> weak_factory_;
   Thread* thread_;
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(FrameRateController);
 };
 
 }  // namespace cc
 
 #endif  // CC_SCHEDULER_FRAME_RATE_CONTROLLER_H_