cc: Making BeginFrameSources support multiple BeginFrameObservers.

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 <set>
 #include <string>
 
@@ skipping 29 matching lines @@
   //  - If the |args| passed to OnBeginFrame is (or *will be*) used, then
   //    LastUsedBeginFrameArgs return value should become the |args| given to
   //    OnBeginFrame.
   //
   //  - If the |args| passed to OnBeginFrame is dropped, then
   //    LastUsedBeginFrameArgs return value should *not* change.
   //
   // These requirements are designed to allow chaining and nesting of
   // BeginFrameObservers which filter the incoming BeginFrame messages while
   // preventing "double dropping" and other bad side effects.
-  virtual const BeginFrameArgs LastUsedBeginFrameArgs() const = 0;
+  virtual const BeginFrameArgs LastUsedBeginFrameArgs() = 0;
 
   // Tracing support
-  virtual void AsValueInto(base::trace_event::TracedValue* dict) const = 0;
+  virtual void AsValueInto(base::trace_event::TracedValue* dict) = 0;
 };
 
 // Simple mix in which implements a BeginFrameObserver which checks the
 // incoming values meet the BeginFrameObserver requirements and implements the
 // required LastUsedBeginFrameArgs behaviour.
 //
 // Users of this mix in should;
 //  - Implement the OnBeginFrameMixInDelegate function.
 //  - Recommended (but not required) to call
 //    BeginFrameObserverMixIn::OnValueInto in their overridden OnValueInto
 //    function.
 class CC_EXPORT BeginFrameObserverMixIn : public BeginFrameObserver {
  public:
   BeginFrameObserverMixIn();
 
   // BeginFrameObserver
 
   // Traces |args| and DCHECK |args| satisfies pre-conditions then calls
   // OnBeginFrameMixInDelegate and updates the last_begin_frame_args_ value on
   // true.
   void OnBeginFrame(const BeginFrameArgs& args) override;
-  const BeginFrameArgs LastUsedBeginFrameArgs() const override;
+  const BeginFrameArgs LastUsedBeginFrameArgs() override;
 
   // Outputs last_begin_frame_args_
-  void AsValueInto(base::trace_event::TracedValue* dict) const override;
+  void AsValueInto(base::trace_event::TracedValue* dict) override;
 
  protected:
   // Subclasses should override this method!
   // Return true if the given argument is (or will be) used.
   virtual bool OnBeginFrameMixInDelegate(const BeginFrameArgs& args) = 0;
 
   BeginFrameArgs last_begin_frame_args_;
   int64_t dropped_begin_frame_args_;
 };
 
@@ skipping 26 matching lines @@
   // in the future this may be extended to allow multiple observers.
   // If making this change, please use base::ObserverList to do so.
   virtual void AddObserver(BeginFrameObserver* obs) = 0;
   virtual void RemoveObserver(BeginFrameObserver* obs) = 0;
 
   // Tells the Source that client is ready to handle BeginFrames messages.
   virtual void SetClientReady() = 0;
 
   // Tracing support - Recommend (but not required) to call this implementation
   // in any override.
-  virtual void AsValueInto(base::trace_event::TracedValue* dict) const = 0;
+  virtual void AsValueInto(base::trace_event::TracedValue* dict) = 0;
 };
 
 // Simple mix in 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 BeginFrameSourceMixIn::AsValueInto
 //    in their own AsValueInto implementation.
 class CC_EXPORT BeginFrameSourceMixIn : public BeginFrameSource {
  public:
-  ~BeginFrameSourceMixIn() override {}
+  ~BeginFrameSourceMixIn() override;
 
   // BeginFrameSource
   bool NeedsBeginFrames() const final;
   void SetNeedsBeginFrames(bool needs_begin_frames) final;
   void DidFinishFrame(size_t remaining_frames) override {}
   void AddObserver(BeginFrameObserver* obs) final;
   void RemoveObserver(BeginFrameObserver* obs) final;
   void SetClientReady() override {}
 
   // Tracing support - Recommend (but not required) to call this implementation
   // in any override.
-  void AsValueInto(base::trace_event::TracedValue* dict) const override;
+  void AsValueInto(base::trace_event::TracedValue* dict) override;
 
  protected:
   BeginFrameSourceMixIn();
 
   // These methods should be used by subclasses to make the call to the
   // observers.
   void CallOnBeginFrame(const BeginFrameArgs& args);
 
   // This method should be overridden if you want to change some behaviour on
   // needs_begin_frames change.
   virtual void OnNeedsBeginFramesChange(bool needs_begin_frames) {}
 
-  BeginFrameObserver* observer_;
+  ObserverList<BeginFrameObserver> observer_list_;
   bool needs_begin_frames_;
 
  private:
   bool inside_as_value_into_;
 };
 
 // A frame source which calls BeginFrame (at the next possible time) as soon as
 // remaining frames reaches zero.
 class CC_EXPORT BackToBackBeginFrameSource : public BeginFrameSourceMixIn {
  public:
   static scoped_ptr<BackToBackBeginFrameSource> Create(
       base::SingleThreadTaskRunner* task_runner);
   ~BackToBackBeginFrameSource() override;
 
   // BeginFrameSource
   void DidFinishFrame(size_t remaining_frames) override;
 
   // Tracing
-  void AsValueInto(base::trace_event::TracedValue* dict) const override;
+  void AsValueInto(base::trace_event::TracedValue* dict) override;
 
  protected:
   explicit BackToBackBeginFrameSource(
       base::SingleThreadTaskRunner* task_runner);
   virtual base::TimeTicks Now();  // Now overridable for testing
 
   base::SingleThreadTaskRunner* task_runner_;
 
   bool send_begin_frame_posted_;
 
@@ skipping 12 matching lines @@
                                             public VSyncParameterObserver,
                                             public TimeSourceClient {
  public:
   static scoped_ptr<SyntheticBeginFrameSource> Create(
       base::SingleThreadTaskRunner* task_runner,
       base::TimeTicks initial_vsync_timebase,
       base::TimeDelta initial_vsync_interval);
   ~SyntheticBeginFrameSource() override;
 
   // Tracing
-  void AsValueInto(base::trace_event::TracedValue* dict) const override;
+  void AsValueInto(base::trace_event::TracedValue* dict) override;
 
   // VSyncParameterObserver
   void OnUpdateVSyncParameters(base::TimeTicks new_vsync_timebase,
                                base::TimeDelta new_vsync_interval) override;
 
   // TimeSourceClient
   void OnTimerTick() override;
 
  protected:
   explicit SyntheticBeginFrameSource(
@@ skipping 22 matching lines @@
   void AddSource(BeginFrameSource* new_source);
   void RemoveSource(BeginFrameSource* existing_source);
   void SetActiveSource(BeginFrameSource* new_source);
   const BeginFrameSource* ActiveSource();
 
   // BeginFrameObserver
   // The mux is an BeginFrameObserver as it needs to proxy the OnBeginFrame
   // calls to preserve the monotonicity of the BeginFrameArgs when switching
   // sources.
   void OnBeginFrame(const BeginFrameArgs& args) override;
-  const BeginFrameArgs LastUsedBeginFrameArgs() const override;
+  const BeginFrameArgs LastUsedBeginFrameArgs() override;
 
   // BeginFrameSource
   void DidFinishFrame(size_t remaining_frames) override;
 
   // BeginFrameSourceMixIn
   void OnNeedsBeginFramesChange(bool needs_begin_frames) override;
 
   // Tracing
-  void AsValueInto(base::trace_event::TracedValue* dict) const override;
+  void AsValueInto(base::trace_event::TracedValue* dict) override;
 
  protected:
   BeginFrameSourceMultiplexer();
   explicit BeginFrameSourceMultiplexer(base::TimeDelta minimum_interval);
 
   bool HasSource(BeginFrameSource* source);
   bool IsIncreasing(const BeginFrameArgs& args);
 
   base::TimeDelta minimum_interval_;
 
   BeginFrameSource* active_source_;
   std::set<BeginFrameSource*> source_list_;
 };
 
 }  // namespace cc
 
 #endif  // CC_SCHEDULER_BEGIN_FRAME_SOURCE_H_