cc: Introduce BeginFrame sequence numbers and acknowledgements.

cc/scheduler/scheduler_state_machine.h

Index: cc/scheduler/scheduler_state_machine.h
diff --git a/cc/scheduler/scheduler_state_machine.h b/cc/scheduler/scheduler_state_machine.h
index b04bd9b85a35ee5d2d90959f25a31b252919ab88..eb60dc40c87bf916d14cf08dae4b9ec7f3268eba 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -5,12 +5,13 @@
 #ifndef CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_
 #define CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_
 
+#include <stdint.h>
+
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "cc/base/cc_export.h"
-#include "cc/output/begin_frame_args.h"
 #include "cc/scheduler/commit_earlyout_reason.h"
 #include "cc/scheduler/draw_result.h"
 #include "cc/scheduler/scheduler_settings.h"
@@ -147,7 +148,7 @@ class CC_EXPORT SchedulerStateMachine {
   // Indicates that the system has entered and left a BeginImplFrame callback.
   // The scheduler will not draw more than once in a given BeginImplFrame
   // callback nor send more than one BeginMainFrame message.
-  void OnBeginImplFrame();
+  void OnBeginImplFrame(uint64_t source_id, uint64_t sequence_number);
   // Indicates that the scheduler has entered the draw phase. The scheduler
   // will not draw more than once in a single draw phase.
   // TODO(sunnyps): Rename OnBeginImplFrameDeadline to OnDraw or similar.
@@ -269,6 +270,14 @@ class CC_EXPORT SchedulerStateMachine {
   void SetVideoNeedsBeginFrames(bool video_needs_begin_frames);
   bool video_needs_begin_frames() const { return video_needs_begin_frames_; }
 
+  bool did_submit_in_last_frame() const { return did_submit_in_last_frame_; }
+  uint64_t last_frame_number_compositor_frame_was_fresh() const {
+    return last_frame_number_compositor_frame_was_fresh_;
+  }
+  uint64_t last_frame_number_active_tree_was_fresh() const {
+    return last_frame_number_active_tree_was_fresh_;
+  }
+
  protected:
   bool BeginFrameRequiredForAction() const;
   bool BeginFrameNeededForVideo() const;
@@ -298,13 +307,17 @@ class CC_EXPORT SchedulerStateMachine {
   BeginMainFrameState begin_main_frame_state_;
   ForcedRedrawOnTimeoutState forced_redraw_state_;
 
-  // These are used for tracing only.
+  // These are used for tracing and BeginFrame acknowledgments.
   int commit_count_;
-  int current_frame_number_;
-  int last_frame_number_submit_performed_;
-  int last_frame_number_draw_performed_;
-  int last_frame_number_begin_main_frame_sent_;
-  int last_frame_number_invalidate_compositor_frame_sink_performed_;
+  uint64_t begin_frame_source_id_;
+  uint64_t current_frame_number_;
+  uint64_t last_frame_number_submit_performed_;
+  uint64_t last_frame_number_draw_performed_;
+  uint64_t last_frame_number_begin_main_frame_sent_;
+  uint64_t last_frame_number_invalidate_compositor_frame_sink_performed_;
+  uint64_t last_frame_number_pending_tree_was_fresh_;
+  uint64_t last_frame_number_active_tree_was_fresh_;
+  uint64_t last_frame_number_compositor_frame_was_fresh_;
 
   // These are used to ensure that an action only happens once per frame,
   // deadline, etc.