Plumb cc::LatencyInfo through command buffer and output surface

cc/output_surface_client.h

Index: cc/output_surface_client.h
diff --git a/cc/output_surface_client.h b/cc/output_surface_client.h
index 2c073b4f750d5815610cb8aeb857f8a898866e30..c046d0c6c37e71c37c59b35d8bd43331c441bcf9 100644
--- a/cc/output_surface_client.h
+++ b/cc/output_surface_client.h
@@ -11,6 +11,7 @@
 namespace cc {
 
 class CompositorFrameAck;
+struct LatencyInfo;
 
 class CC_EXPORT OutputSurfaceClient {
  public:
@@ -18,6 +19,8 @@ class CC_EXPORT OutputSurfaceClient {
                                         base::TimeDelta interval) = 0;
   virtual void OnSendFrameToParentCompositorAck(const CompositorFrameAck&) = 0;
 
+  virtual void OnReceivedLatencyInfo(const LatencyInfo&) = 0;

[nduca, 2013/03/18 18:38:31]

I think we should consider merging SwapBuffers/SendFrameData into one method on
the output surface and always passing latency info on that command.

And, doing the same for the swapbuffers ack && frame data ack.

[piman, 2013/03/19 04:30:29]

At a high level, what is the purpose of making LatencyInfo flow back into the
compositor? Is it just so that we can display it? Or are we trying to measure
something with it, or use it to make decisions in the compositor?

+
  protected:
   virtual ~OutputSurfaceClient() {}
 };