Pipe impl_latency_takes_priority_ to the RenderScheduler.

cc/scheduler/scheduler.cc

Index: cc/scheduler/scheduler.cc
diff --git a/cc/scheduler/scheduler.cc b/cc/scheduler/scheduler.cc
index 0d90c68214f15a822f66419d899885b7a4e84e56..0ccc094b7ff38eb3669fb8efd981a8a13fca0fd6 100644
--- a/cc/scheduler/scheduler.cc
+++ b/cc/scheduler/scheduler.cc
@@ -354,6 +354,7 @@ bool Scheduler::OnBeginFrameMixInDelegate(const BeginFrameArgs& args) {
   // TODO(brianderson): Adjust deadline in the DisplayScheduler.
   BeginFrameArgs adjusted_args(args);
   adjusted_args.deadline -= EstimatedParentDrawTime();

[Sami, 2015/06/08 11:47:53]

Another option would be to communicate this through the deadline. For example if
your deadline is zero then you won't be on the critical path.

+  adjusted_args.on_critical_path = MainThreadOnCriticalPath();
 
   // Deliver BeginFrames to children.
   // TODO(brianderson): Move this responsibility to the DisplayScheduler.