[cc] Set BeginFrame sequence numbers on CompositorFrames from Scheduler.

cc/scheduler/scheduler.cc

 // Copyright 2011 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.
 
 #include "cc/scheduler/scheduler.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
@@ skipping 780 matching lines @@
   return estimated_draw_time < args.deadline;
 }
 
 bool Scheduler::IsBeginMainFrameSentOrStarted() const {
   return (state_machine_.begin_main_frame_state() ==
               SchedulerStateMachine::BEGIN_MAIN_FRAME_STATE_SENT ||
           state_machine_.begin_main_frame_state() ==
               SchedulerStateMachine::BEGIN_MAIN_FRAME_STATE_STARTED);
 }
 
+BeginFrameAck Scheduler::CurrentBeginFrameAckForActiveTree() const {
+  return BeginFrameAck(
+      begin_main_frame_args_.source_id, begin_main_frame_args_.sequence_number,
+      state_machine_.last_begin_frame_sequence_number_active_tree_was_fresh(),
+      0, true);
+}
+
 }  // namespace cc