cc: Remove retro frames from scheduler.

cc/scheduler/begin_frame_source.h

 // Copyright 2014 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_BEGIN_FRAME_SOURCE_H_
 #define CC_SCHEDULER_BEGIN_FRAME_SOURCE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 48 matching lines @@
   // BeginFrameObservers which filter the incoming BeginFrame messages while
   // preventing "double dropping" and other bad side effects.
   virtual const BeginFrameArgs& LastUsedBeginFrameArgs() const = 0;
 
   virtual void OnBeginFrameSourcePausedChanged(bool paused) = 0;
 
   // Tracing support
   virtual void AsValueInto(base::trace_event::TracedValue* dict) const = 0;
 };
 
-// Simple base class which implements a BeginFrameObserver which checks the
-// incoming values meet the BeginFrameObserver requirements and implements the
-// required LastUsedBeginFrameArgs behaviour.
-//
-// Users of this class should;
-//  - Implement the OnBeginFrameDerivedImpl function.
-//  - Recommended (but not required) to call
-//    BeginFrameObserverBase::OnValueInto in their overridden OnValueInto
-//    function.
-class CC_EXPORT BeginFrameObserverBase : public BeginFrameObserver {

[enne (OOO), 2016/04/14 23:02:26]

Hmm, this was useful because it implemented some functions like
LastUsedBeginFrameArgs and AsValueInto automatically.  I was going to use these
in https://codereview.chromium.org/1841083007/.  Maybe it should just be wrapped
into the base class or there's some other cleanup that makes sense.  What do you
think?

- public:
-  BeginFrameObserverBase();
-
-  // BeginFrameObserver
-
-  // Traces |args| and DCHECK |args| satisfies pre-conditions then calls
-  // OnBeginFrameDerivedImpl and updates the last_begin_frame_args_ value on
-  // true.
-  void OnBeginFrame(const BeginFrameArgs& args) override;
-  const BeginFrameArgs& LastUsedBeginFrameArgs() const override;
-
-  // Outputs last_begin_frame_args_
-  void AsValueInto(base::trace_event::TracedValue* dict) const override;
-
- protected:
-  // Subclasses should override this method!
-  // Return true if the given argument is (or will be) used.
-  virtual bool OnBeginFrameDerivedImpl(const BeginFrameArgs& args) = 0;
-
-  BeginFrameArgs last_begin_frame_args_;
-  int64_t dropped_begin_frame_args_;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(BeginFrameObserverBase);
-};
-
 // Interface for a class which produces BeginFrame calls to a
 // BeginFrameObserver.
 //
 // BeginFrame calls *normally* occur just after a vsync interrupt when input
 // processing has been finished and provide information about the time values
 // of the vsync times. *However*, these values can be heavily modified or even
 // plain made up (when no vsync signal is available or vsync throttling is
 // turned off). See the BeginFrameObserver for information about the guarantees
 // all BeginFrameSources *must* provide.
 class CC_EXPORT BeginFrameSource {
  public:
   virtual ~BeginFrameSource() {}
 
   // DidFinishFrame provides back pressure to a frame source about frame
   // processing (rather than toggling SetNeedsBeginFrames every frame). It is
   // used by systems like the BackToBackFrameSource to make sure only one frame
   // is pending at a time.
-  virtual void DidFinishFrame(size_t remaining_frames) = 0;
+  virtual void DidFinishFrame(BeginFrameObserver* obs) = 0;
 
   // Add/Remove an observer from the source. When no observers are added the BFS
   // should shut down its timers, disable vsync, etc.
   virtual void AddObserver(BeginFrameObserver* obs) = 0;
   virtual void RemoveObserver(BeginFrameObserver* obs) = 0;
 
   // Tracing support - Recommend (but not required) to call this implementation
   // in any override.
   virtual void AsValueInto(base::trace_event::TracedValue* dict) const = 0;
 };
 
 // Simple base class which implements a BeginFrameSource.
 // Implementation classes should:
 //  - Implement the pure virtual (Set)NeedsBeginFrames methods from
 //    BeginFrameSource.
 //  - Use the CallOnBeginFrame method to call to the observer(s).
 //  - Recommended (but not required) to call BeginFrameSourceBase::AsValueInto
 //    in their own AsValueInto implementation.
 class CC_EXPORT BeginFrameSourceBase : public BeginFrameSource {
  public:
   ~BeginFrameSourceBase() override;
 
   // BeginFrameSource
-  void DidFinishFrame(size_t remaining_frames) override {}
+  void DidFinishFrame(BeginFrameObserver* obs) override {}
   void AddObserver(BeginFrameObserver* obs) override;
   void RemoveObserver(BeginFrameObserver* obs) override;
 
   // Tracing support - Recommend (but not required) to call this implementation
   // in any override.
   void AsValueInto(base::trace_event::TracedValue* dict) const override;
 
  protected:
   BeginFrameSourceBase();
 
@@ skipping 18 matching lines @@
 };
 
 // A frame source which calls BeginFrame (at the next possible time) as soon as
 // remaining frames reaches zero.
 class CC_EXPORT BackToBackBeginFrameSource : public BeginFrameSourceBase {
  public:
   explicit BackToBackBeginFrameSource(
       base::SingleThreadTaskRunner* task_runner);
   ~BackToBackBeginFrameSource() override;
 
-  // BeginFrameSource
-  void DidFinishFrame(size_t remaining_frames) override;
-
   // BeginFrameSourceBase
+  void DidFinishFrame(BeginFrameObserver* obs) override;
   void AddObserver(BeginFrameObserver* obs) override;
   void OnNeedsBeginFramesChanged(bool needs_begin_frames) override;
 
   // Tracing
   void AsValueInto(base::trace_event::TracedValue* dict) const override;
 
  protected:
   virtual base::TimeTicks Now();  // Now overridable for testing
 
   base::SingleThreadTaskRunner* task_runner_;
@@ skipping 16 matching lines @@
   explicit SyntheticBeginFrameSource(base::SingleThreadTaskRunner* task_runner,
                                      base::TimeDelta initial_vsync_interval);
   explicit SyntheticBeginFrameSource(
       std::unique_ptr<DelayBasedTimeSource> time_source);
   ~SyntheticBeginFrameSource() override;
 
   void OnUpdateVSyncParameters(base::TimeTicks new_vsync_timebase,
                                base::TimeDelta new_vsync_interval);
 
   // BeginFrameSourceBase
+  void DidFinishFrame(BeginFrameObserver* obs) override;
   void AddObserver(BeginFrameObserver* obs) override;
   void OnNeedsBeginFramesChanged(bool needs_begin_frames) override;
 
   // Tracing
   void AsValueInto(base::trace_event::TracedValue* dict) const override;
 
   // DelayBasedTimeSourceClient
   void OnTimerTick() override;
 
  protected:
   BeginFrameArgs CreateBeginFrameArgs(base::TimeTicks frame_time,
                                       BeginFrameArgs::BeginFrameArgsType type);
 
   std::unique_ptr<DelayBasedTimeSource> time_source_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyntheticBeginFrameSource);
 };
 
 }  // namespace cc
 
 #endif  // CC_SCHEDULER_BEGIN_FRAME_SOURCE_H_