ServiceWorker: Use scheduler's default task queue for posting tasks on main thread

ServiceWorker: Use scheduler's default task queue for posting tasks on main thread

This fixes a task ordering bug between WebMessagePortChannelImpl and
ServiceWorkerScriptContext. The former posts tasks via the Blink
scheduler's default task queue, and the latter was using the MessageLoop
directly. This patch makes tasks from service worker to the main thread
go through the scheduler.

BUG=460833
TEST=http/tests/serviceworker/postmessage-msgport-to-client.html

Committed: https://crrev.com/a7fe515e3ca07e260b58ebf460f842601266ed87
Cr-Commit-Position: refs/heads/master@{#318022}

[Kunihiko Sakamoto, 2015-02-25 06:26:10]

ksakamoto@chromium.org changed reviewers:
+ kinuko@chromium.org, skyostil@chromium.org

[kinuko, 2015-02-25 07:00:54]

lgtm

[Sami, 2015-02-25 10:54:48]

lgtm, thanks!

[Kunihiko Sakamoto, 2015-02-25 10:56:05]

The CQ bit was checked by ksakamoto@chromium.org

[commit-bot: I haz the power, 2015-02-25 10:56:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/958523002/1

[commit-bot: I haz the power, 2015-02-25 10:59:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-25 11:00:02]

Patchset 1 (id:??) landed as
https://crrev.com/a7fe515e3ca07e260b58ebf460f842601266ed87
Cr-Commit-Position: refs/heads/master@{#318022}

[phoglund_chromium, 2015-02-25 14:00:33]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/954993002/ by phoglund@chromium.org.

The reason for reverting is: Highly speculative revert after views_unittests
broke on win7:

http://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%28...

c:\b\build\slave\win_builder__dbg_\build\src\ui\views\accessibility\native_view_accessibility_win_unittest.cc(190):
error: Value of: infobar_accessible.IsSameObject(targets[0])

This patch does change task queuing, which makes it seem slightly more likely to
break stuff than the others in the blamelist..

[phoglund_chromium, 2015-02-25 14:32:19]

Win7 appears to green up, so I think this revert may have been correct. I can
also see the same test break on win xp; let's see if those bots cycle green as
well after they pick up the revert.

[phoglund_chromium, 2015-02-25 16:25:55]

On 2015/02/25 14:32:19, phoglund wrote:
> Win7 appears to green up, so I think this revert may have been correct. I can
> also see the same test break on win xp; let's see if those bots cycle green as
> well after they pick up the revert.

Hmm, no, I just saw another flake of the same test on the Vista bot, so I'll
reinstate this patch.