cc: Poll for state that triggers draws (synchronous compositor only)

cc: Poll for state that triggers draws (synchronous compositor only)

This adds Scheduler::PollForAnticipatedDrawTriggers which is used
by the synchronous compositor to avoid requesting BeginImplFrames
when we might not actually draw new content, but still need to
monitor state that might trigger a draw at vsync intervals.

This can occur, for example, when the last swap used incomplete tiles
(checkerboards or low-quality) or when a commit is aborted and we
want to wait a vsync before starting the next commit.

BUG=284810
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=222711

[brianderson, 2013-09-04 01:32:52]

Bo, can you see if this fixes the issue in http://b/10533873 ?

[boliu, 2013-09-04 03:50:02]

On 2013/09/04 01:32:52, Brian Anderson wrote:
> Bo, can you see if this fixes the issue in http://b/10533873 ?

The issue is not reliably reproducible. I tried for 15 minutes and didn't
reproduce it, and it used to occur more frequently than that. So I think this
does fix the bug.

[danakj, 2013-09-04 13:08:56]

Can we have tests?

[brianderson, 2013-09-11 23:19:31]

https://codereview.chromium.org/23463014/diff/10001/cc/trees/layer_tree_host_...
File cc/trees/layer_tree_host_unittest.cc (right):

https://codereview.chromium.org/23463014/diff/10001/cc/trees/layer_tree_host_...
cc/trees/layer_tree_host_unittest.cc:2407: class
LayerTreeHostTestAbortedCommitDoesntStallNextCommitWhenIdle
This test times out without the fix in this patch.

[enne (OOO), 2013-09-11 23:28:11]

lgtm.  Thanks for writing a test!

https://codereview.chromium.org/23463014/diff/10001/cc/trees/layer_tree_host_...
File cc/trees/layer_tree_host_unittest.cc (right):

https://codereview.chromium.org/23463014/diff/10001/cc/trees/layer_tree_host_...
cc/trees/layer_tree_host_unittest.cc:2411: : commit_count_(0) {}
style nit: this needs to be indented.

https://codereview.chromium.org/23463014/diff/10001/cc/trees/layer_tree_host_...
cc/trees/layer_tree_host_unittest.cc:2432: virtual void
CommitCompleteOnThread(LayerTreeHostImpl *host_impl) OVERRIDE {
style nit: '* ' not ' *'

https://codereview.chromium.org/23463014/diff/10001/cc/trees/layer_tree_host_...
cc/trees/layer_tree_host_unittest.cc:2437: virtual void AfterTest() OVERRIDE {}
As a sanity check for this test, can you also check that the number of
CommitCompleteOnThread calls is two (or at least one?) so that you know for sure
that the commit was aborted?

[commit-bot: I haz the power, 2013-09-11 23:50:21]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/brianderson@chromium.org/23463014/7001

[commit-bot: I haz the power, 2013-09-12 00:04:11]

Step "update" is always a major failure.
Look at the try server FAQ for more details.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_clan...

[commit-bot: I haz the power, 2013-09-12 01:04:30]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/brianderson@chromium.org/23463014/7001

[commit-bot: I haz the power, 2013-09-12 05:27:54]

Change committed as 222711