cc: ReadyToDraw notifications.

cc/scheduler/scheduler.cc

Index: cc/scheduler/scheduler.cc
diff --git a/cc/scheduler/scheduler.cc b/cc/scheduler/scheduler.cc
index 88c27c103e33fe2d85302772a302663515a5715c..270aacec748e6fac45e2b036de7c2c27a9f910af 100644
--- a/cc/scheduler/scheduler.cc
+++ b/cc/scheduler/scheduler.cc
@@ -197,6 +197,11 @@ void Scheduler::NotifyReadyToActivate() {
   ProcessScheduledActions();
 }
 
+void Scheduler::NotifyReadyToDraw() {
+  // Empty for now, until we take action based on the notification as part of
+  // crbugs 352894, 383157, 421923.

[reveman, 2014/10/28 15:52:24]

Could we at least make this perform a UpdateVisibleTiles/CheckForCompletedTasks
check so that we redraw if we have initialized visible tiles?

[enne (OOO), 2014/10/28 19:07:47]

+danakj

[reveman, 2014/10/28 19:20:10]

Never mind. I see that you already have this check in
TileManager::CheckIfReadyToDraw().

We might want to remove the scheduler plumbing from this patch as it's not used
yet and land the part up to the CheckForCompletedTasks in the TileManager for
now as that is useful on its own.

[brianderson, 2014/10/28 22:11:07]

We'll use this notification in the Scheduler very soon, so keeping it in this
patch seems fine.

Somewhat related to the UpdateVisibleTiles stuff is
https://codereview.chromium.org/671653005.  Looks like Dana want's to move the
responsibility entirely over to the TileManager.

[danakj, 2014/10/31 17:07:55]

I think this plumbing can go away. We can just SetNeedsRedraw from LTHI when we
want to draw something.

[brianderson, 2014/10/31 23:04:24]

NotifyReadyToDraw will indicate that we can draw without checkerboarding.
SetNeedsRedraw only indicates that we have something new to draw without any
guarantees about checkerboarding.

Once the scheduler has NotifyReadyToDraw, I'm imaging the scheduler will do the
following:
1) Change AdjustBeginImplFrameDeadline to not post the deadline immediately.
2) Then trigger the deadline early only once we get the NotifyReadyToDraw
signal.

Today, we get away without the above because of prepainting. Newly visible tiles
are usually ready. With Ganesh, we plan to move away from prepainting and it
will become much more important to check for checkerboarding before we draw.

[danakj, 2014/11/03 16:11:12]

Interesting, how does that play out with other sources of SetNeedsRedraw besides
invalidation? Such as a layer moving on the screen causing damage and calling
SetNeedsRedraw?

+}
+
 void Scheduler::SetNeedsCommit() {
   state_machine_.SetNeedsCommit();
   ProcessScheduledActions();