Remove MessageLoop::current() from ppapi/proxy.

Remove MessageLoop::current() from ppapi/proxy.

Whenever possible, use ThreadTaskRunnerHandle::Get() instead of
MessageLoop::current(). ThreadTaskRunnerHandle::Get() works within
TaskScheduler while MessageLoop::current() doesn't.

Good reasons to use MessageLoop::current():
- Add destruction, nesting or task observers.
- Run nested loops.

Bad reasons to use MessageLoop::current():
- Post tasks. Use ThreadTaskRunnerHandle::Get() instead.
- Watch a file descriptor. Use FileDescriptorWatcher instead.
- Verify that it is possible to post tasks to the current thread.
  Use ThreadTaskRunnerHandle::IsSet() instead.
- Verify that code runs on a specific thread. Use
  SingleThreadTaskRunner::BelongsToCurrentThread() instead.

BUG=650723
Committed: https://crrev.com/2111a57d06c915dce0a96bdfd2cffba284cf53c6
Cr-Commit-Position: refs/heads/master@{#424863}

[fdoray, 2016-10-11 17:53:41]

The CQ bit was checked by fdoray@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-10-11 17:54:00]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-11 18:17:51]

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

[commit-bot: I haz the power, 2016-10-11 18:17:51]

Dry run: Try jobs failed on following builders:
  cast_shell_linux on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)

[fdoray, 2016-10-12 17:07:10]

The CQ bit was checked by fdoray@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-10-12 17:07:42]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-12 17:59:30]

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

[commit-bot: I haz the power, 2016-10-12 17:59:31]

Dry run: This issue passed the CQ dry run.

[fdoray, 2016-10-12 19:59:48]

fdoray@chromium.org changed reviewers:
+ piman@chromium.org

[fdoray, 2016-10-12 19:59:48]

PTAL

[piman, 2016-10-12 20:50:29]

lgtm

[fdoray, 2016-10-12 21:16:31]

The CQ bit was checked by fdoray@chromium.org

[commit-bot: I haz the power, 2016-10-12 21:17:01]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-12 21:28:17]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-10-12 21:31:40]

Description was changed from

==========
Remove MessageLoop::current() from ppapi/proxy.

Whenever possible, use ThreadTaskRunnerHandle::Get() instead of
MessageLoop::current(). ThreadTaskRunnerHandle::Get() works within
TaskScheduler while MessageLoop::current() doesn't.

Good reasons to use MessageLoop::current():
- Add destruction, nesting or task observers.
- Run nested loops.

Bad reasons to use MessageLoop::current():
- Post tasks. Use ThreadTaskRunnerHandle::Get() instead.
- Watch a file descriptor. Use FileDescriptorWatcher instead.
- Verify that it is possible to post tasks to the current thread.
  Use ThreadTaskRunnerHandle::IsSet() instead.
- Verify that code runs on a specific thread. Use
  SingleThreadTaskRunner::BelongsToCurrentThread() instead.

BUG=650723
==========

to

==========
Remove MessageLoop::current() from ppapi/proxy.

Whenever possible, use ThreadTaskRunnerHandle::Get() instead of
MessageLoop::current(). ThreadTaskRunnerHandle::Get() works within
TaskScheduler while MessageLoop::current() doesn't.

Good reasons to use MessageLoop::current():
- Add destruction, nesting or task observers.
- Run nested loops.

Bad reasons to use MessageLoop::current():
- Post tasks. Use ThreadTaskRunnerHandle::Get() instead.
- Watch a file descriptor. Use FileDescriptorWatcher instead.
- Verify that it is possible to post tasks to the current thread.
  Use ThreadTaskRunnerHandle::IsSet() instead.
- Verify that code runs on a specific thread. Use
  SingleThreadTaskRunner::BelongsToCurrentThread() instead.

BUG=650723

Committed: https://crrev.com/2111a57d06c915dce0a96bdfd2cffba284cf53c6
Cr-Commit-Position: refs/heads/master@{#424863}
==========

[commit-bot: I haz the power, 2016-10-12 21:31:41]

Patchset 2 (id:??) landed as
https://crrev.com/2111a57d06c915dce0a96bdfd2cffba284cf53c6
Cr-Commit-Position: refs/heads/master@{#424863}