NotifyAllTileTasksCompleted for synchronous renderer compositor

NotifyAllTileTasksCompleted for synchronous renderer compositor

This change ensures that in cases where no work is enqueued on the tile manager when we background, the NotifyAllTileTasksCompleted signal is still delivered.

Added a test to ensure that we call the appropriate callback in the synchronous renderer case.

BUG=505495
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1228323004

Cr-Commit-Position: refs/heads/master@{#338589}
(cherry picked from commit 0e28d110ce80a66d42268cce003e792edfef0006)

NOTRY=true
NOPRESUBMIT=true
TBR=enne

[ericrk, 2015-07-15 19:48:43]

ericrk@chromium.org changed reviewers:
+ boliu@chromium.org

[ericrk, 2015-07-15 19:49:15]

ericrk@chromium.org changed reviewers:
+ enne@chromium.org
- boliu@chromium.org

[ericrk, 2015-07-15 19:50:14]

Merging into M45 - have approval.

[ericrk, 2015-07-15 22:30:30]

The CQ bit was checked by ericrk@chromium.org

[commit-bot: I haz the power, 2015-07-15 22:31:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1233003004/1

[commit-bot: I haz the power, 2015-07-15 22:31:12]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-07-15 22:31:13]

No L-G-T-M from a valid reviewer yet. Only full committers are accepted.
Even if an L-G-T-M may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[boliu, 2015-07-15 22:32:23]

On 2015/07/15 22:31:13, commit-bot: I haz the power wrote:
> No L-G-T-M from a valid reviewer yet. Only full committers are accepted.
> Even if an L-G-T-M may have been provided, it was from a non-committer,
> _not_ a full super star committer.
> See http://www.chromium.org/getting-involved/become-a-committer
> Note that this has nothing to do with OWNERS files.

commiter stamp lgtm

[boliu, 2015-07-15 22:32:36]

The CQ bit was checked by boliu@chromium.org

[commit-bot: I haz the power, 2015-07-15 22:34:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1233003004/1

[commit-bot: I haz the power, 2015-07-15 22:37:11]

Committed patchset #1 (id:1)