cc: Always use SetNeedsBeginFrame to request the next BeginFrame

cc/scheduler/scheduler_state_machine.cc

Index: cc/scheduler/scheduler_state_machine.cc
diff --git a/cc/scheduler/scheduler_state_machine.cc b/cc/scheduler/scheduler_state_machine.cc
index 009cf4bdb59e61ecaf44ae268efc1359caf24a19..355d36c7acfd546287a3b7efcdfcac85c1330ba2 100644
--- a/cc/scheduler/scheduler_state_machine.cc
+++ b/cc/scheduler/scheduler_state_machine.cc
@@ -740,6 +740,13 @@ bool SchedulerStateMachine::ProactiveBeginFrameWantedByImplThread() const {
   if (has_pending_tree_)
     return true;
 
+  // If we just swapped, it's likely that we are going to produce another
+  // frame soon. This helps avoid negative glitches in our SetNeedsBeginFrame
+  // requests, which may propagate to the BeginFrame provider and get sampled
+  // at an innpportune time, delaying the next BeginFrame.

[enne (OOO), 2013/09/13 18:39:19]

speling

+  if (last_frame_number_swap_performed_ == current_frame_number_)
+    return true;
+
   return false;
 }