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

cc/scheduler/scheduler.h

Index: cc/scheduler/scheduler.h
diff --git a/cc/scheduler/scheduler.h b/cc/scheduler/scheduler.h
index 48a1b1ed82c0fbbb9ad110c99a3399923987eafa..2f086fd8a9bdd12c696022178fad69503a80d514 100644
--- a/cc/scheduler/scheduler.h
+++ b/cc/scheduler/scheduler.h
@@ -142,6 +142,10 @@ class CC_EXPORT Scheduler : public BeginFrameObserverBase {
     return begin_frame_source_;
   }
 
+  uint32_t CurrentBeginFrameSourceId() const;
+  uint64_t CurrentBeginFrameSequenceNumber() const;
+  uint64_t LatestConfirmedBeginFrameSequenceNumberForActiveTree() const;

[brianderson, 2017/02/24 01:08:36]

Can these be collapsed into a single getter called CurrentBeginFrameAck that
either takes an Ack as an output argument or returns an Ack?

[Eric Seckler, 2017/02/27 11:50:32]

Done.

+
  protected:
   // Virtual for testing.
   virtual base::TimeTicks Now() const;