Added ability to dynamically toggle frame throttling in the scheduler.

cc/scheduler/scheduler.h

Index: cc/scheduler/scheduler.h
diff --git a/cc/scheduler/scheduler.h b/cc/scheduler/scheduler.h
index dea7c3e541004fd0bce31f182b501ca0e16be845..addd5aa5717c87df084b1c296d89b0c4840179d5 100644
--- a/cc/scheduler/scheduler.h
+++ b/cc/scheduler/scheduler.h
@@ -65,6 +65,8 @@ class CC_EXPORT SchedulerFrameSourcesConstructor {
   virtual BeginFrameSource* ConstructPrimaryFrameSource(Scheduler* scheduler);
   virtual BeginFrameSource* ConstructBackgroundFrameSource(
       Scheduler* scheduler);
+  virtual BeginFrameSource* ConstructUnthrottledFrameSource(
+      Scheduler* scheduler);
 
  protected:
   SchedulerFrameSourcesConstructor() {}
@@ -112,6 +114,7 @@ class CC_EXPORT Scheduler : public BeginFrameObserverMixIn,
   void SetCanDraw(bool can_draw);
   void NotifyReadyToActivate();
   void NotifyReadyToDraw();
+  void SetThrottleFrameProduction(bool throttle);
 
   void SetNeedsCommit();
 
@@ -184,12 +187,15 @@ class CC_EXPORT Scheduler : public BeginFrameObserverMixIn,
   scoped_ptr<BeginFrameSourceMultiplexer> frame_source_;
   BeginFrameSource* primary_frame_source_;
   BeginFrameSource* background_frame_source_;
+  BeginFrameSource* unthrottled_frame_source_;

[enne (OOO), 2014/12/15 23:21:07]

Maybe it's not possible, but I kind of wish that this was a detail that the
scheduler didn't have to know about.  BeginFrameSource itself is pretty
abstract, so it seems like it could be possible to make the external begin frame
source implement this unthrottled setting and then the scheduler doesn't have to
know anything about it.

(Also, when the devtools button is clicked, does both the renderer and the
browser need to use unthrottled frames? Or, is this just a renderer thing?)

[brianderson, 2014/12/16 22:36:42]

We could move the existing internal synthetic BeginFrame sources just outside
into the Proxy, then pass in a BeginFrameSourceMultiplexer as the primary
source, but we'd have to duplicate logic for both TP and STP. It would clean up
the scheduler, but complicate the proxies. I have a slight preference for the
way Brandon currently has it.
Once the Browser switches over to using the STP w/ scheduler, we'll need to pipe
the selection over to the Browser as well so that it can also use the
unthrottled source. Otherwise it will indirectly swap ack limit the Renderer.
Might be a little annoying to track how many Renderers are unthrottled to decide
whether the Browser should also be unthrottled.

 
   // Storage when frame sources are internal
   scoped_ptr<BeginFrameSource> primary_frame_source_internal_;
   scoped_ptr<SyntheticBeginFrameSource> background_frame_source_internal_;
+  scoped_ptr<BeginFrameSource> unthrottled_frame_source_internal_;
 
   VSyncParameterObserver* vsync_observer_;
+  bool throttle_frame_production_;
 
   const SchedulerSettings settings_;
   SchedulerClient* client_;
@@ -238,6 +244,7 @@ class CC_EXPORT Scheduler : public BeginFrameObserverMixIn,
   void PollToAdvanceCommitState();
   void SetupPowerMonitoring();
   void TeardownPowerMonitoring();
+  void UpdateActiveFrameSource();
 
   base::TimeDelta EstimatedParentDrawTime() {
     return estimated_parent_draw_time_;