cc: Introduce BeginFrame sequence numbers and acknowledgements.

cc/surfaces/display_scheduler.h

Index: cc/surfaces/display_scheduler.h
diff --git a/cc/surfaces/display_scheduler.h b/cc/surfaces/display_scheduler.h
index f6822878936393bdf001ac42ec42a2f3bd778200..c5e463ac3d199ddf2a5fd59049ed34af1f532f46 100644
--- a/cc/surfaces/display_scheduler.h
+++ b/cc/surfaces/display_scheduler.h
@@ -13,13 +13,12 @@
 #include "base/single_thread_task_runner.h"
 #include "cc/output/renderer_settings.h"
 #include "cc/scheduler/begin_frame_source.h"
+#include "cc/surfaces/display_begin_frame_source.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
 
 namespace cc {
 
-class BeginFrameSource;
-
 class CC_SURFACES_EXPORT DisplaySchedulerClient {
  public:
   virtual ~DisplaySchedulerClient() {}
@@ -27,14 +26,15 @@ class CC_SURFACES_EXPORT DisplaySchedulerClient {
   virtual bool DrawAndSwap() = 0;
 };
 
-class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
+class CC_SURFACES_EXPORT DisplayScheduler
+    : public DisplayBeginFrameSourceClient {
  public:
-  DisplayScheduler(BeginFrameSource* begin_frame_source,
-                   base::SingleThreadTaskRunner* task_runner,
+  DisplayScheduler(base::SingleThreadTaskRunner* task_runner,
                    int max_pending_swaps);
-  ~DisplayScheduler() override;
+  virtual ~DisplayScheduler();
 
   void SetClient(DisplaySchedulerClient* client);
+  void SetBeginFrameSource(DisplayBeginFrameSource* begin_frame_source);
 
   void SetVisible(bool visible);
   void SetRootSurfaceResourcesLocked(bool locked);
@@ -48,25 +48,28 @@ class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
 
   void OutputSurfaceLost();
 
-  // BeginFrameObserverBase implementation
-  bool OnBeginFrameDerivedImpl(const BeginFrameArgs& args) override;
-  void OnBeginFrameSourcePausedChanged(bool paused) override;
+  // DisplayBeginFrameSourceClient implementation.
+  void BeginFrameObserverStatusChanged() override;
+  void OnBeginFrame(const BeginFrameArgs& args) override;
+  const BeginFrameArgs& LastUsedBeginFrameArgs() const override;
 
  protected:
   base::TimeTicks DesiredBeginFrameDeadlineTime();
   virtual void ScheduleBeginFrameDeadline();
-  void AttemptDrawAndSwap();
+  bool AttemptDrawAndSwap();
   void OnBeginFrameDeadline();
-  void DrawAndSwap();
+  bool DrawAndSwap();
   void StartObservingBeginFrames();
   void StopObservingBeginFrames();
   bool ShouldDraw();
+  void FinishFrame(bool did_draw);
 
   DisplaySchedulerClient* client_;
-  BeginFrameSource* begin_frame_source_;
+  DisplayBeginFrameSource* begin_frame_source_;
   base::SingleThreadTaskRunner* task_runner_;
 
   BeginFrameArgs current_begin_frame_args_;
+  BeginFrameArgs last_used_begin_frame_args_;
   base::Closure begin_frame_deadline_closure_;
   base::CancelableClosure begin_frame_deadline_task_;
   base::TimeTicks begin_frame_deadline_task_time_;
@@ -81,20 +84,13 @@ class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
   bool inside_begin_frame_deadline_interval_;
   bool needs_draw_;
   bool expecting_root_surface_damage_because_of_resize_;
-  bool all_active_child_surfaces_ready_to_draw_;
 
   int pending_swaps_;
   int max_pending_swaps_;
 
-  bool observing_begin_frame_source_;
+  bool observing_begin_frames_;
 
   SurfaceId root_surface_id_;
-  bool root_surface_damaged_;
-  bool expect_damage_from_root_surface_;
-
-  std::set<SurfaceId> child_surface_ids_damaged_;
-  std::set<SurfaceId> child_surface_ids_damaged_prev_;
-  std::vector<SurfaceId> child_surface_ids_to_expect_damage_from_;
 
   base::WeakPtrFactory<DisplayScheduler> weak_ptr_factory_;