cc: Handle retroactive BeginFrames 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 7d577b0187ac334a9324f407990121a2f082eeb2..46607e4228dd79fab4be5e553f2e9e6106f60b1e 100644
--- a/cc/scheduler/scheduler.h
+++ b/cc/scheduler/scheduler.h
@@ -5,6 +5,7 @@
 #ifndef CC_SCHEDULER_SCHEDULER_H_
 #define CC_SCHEDULER_SCHEDULER_H_
 
+#include <deque>
 #include <string>
 
 #include "base/basictypes.h"
@@ -24,7 +25,8 @@ class Thread;
 
 class SchedulerClient {
  public:
-  virtual void SetNeedsBeginImplFrame(bool enable) = 0;
+  virtual void SetNeedsBeginFrame(bool enable) = 0;
+  virtual void WillBeginImplFrame(const BeginFrameArgs& args) = 0;
   virtual void ScheduledActionSendBeginMainFrame() = 0;
   virtual DrawSwapReadbackResult ScheduledActionDrawAndSwapIfPossible() = 0;
   virtual DrawSwapReadbackResult ScheduledActionDrawAndSwapForced() = 0;
@@ -110,6 +112,8 @@ class CC_EXPORT Scheduler {
 
   base::TimeTicks LastBeginImplFrameTime();
 
+  void BeginFrame(const BeginFrameArgs& args);
+  void BeginRetroFrame();
   void BeginImplFrame(const BeginFrameArgs& args);
   void OnBeginImplFrameDeadline();
   void PollForAnticipatedDrawTriggers();
@@ -128,9 +132,10 @@ class CC_EXPORT Scheduler {
             int layer_tree_host_id,
             const scoped_refptr<base::SequencedTaskRunner>& impl_task_runner);
 
-  base::TimeTicks AdjustedBeginImplFrameDeadline() const;
+  base::TimeTicks AdjustedBeginImplFrameDeadline(
+      const BeginFrameArgs& args) const;
   void ScheduleBeginImplFrameDeadline(base::TimeTicks deadline);
-  void SetupNextBeginImplFrameIfNeeded();
+  void SetupNextBeginFrameIfNeeded();
   void ActivatePendingTree();
   void DrawAndSwapIfPossible();
   void DrawAndSwapForced();
@@ -147,8 +152,12 @@ class CC_EXPORT Scheduler {
   int layer_tree_host_id_;
   scoped_refptr<base::SequencedTaskRunner> impl_task_runner_;
 
-  bool last_set_needs_begin_impl_frame_;
-  BeginFrameArgs last_begin_impl_frame_args_;
+  bool last_set_needs_begin_frame_;
+  bool begin_retro_frame_posted_;
+
+  std::deque<BeginFrameArgs> begin_retro_frame_args_;
+  BeginFrameArgs begin_impl_frame_args_;
+
   base::CancelableClosure begin_impl_frame_deadline_closure_;
   base::CancelableClosure poll_for_draw_triggers_closure_;
   base::RepeatingTimer<Scheduler> advance_commit_state_timer_;