Use FileDescriptorWatcher in ProcessOutputWatcher

Use FileDescriptorWatcher in ProcessOutputWatcher

This allows ProcessOutputWatcher to be used from any thread that
instantiates a FileDescriptorWatcher (not just threads that run
a MessageLoopForIO). This will facilitate the migration of
BrowserThreads to base/task_scheduler.

BUG=645114
Committed: https://crrev.com/0bd9f1a1ba8ea5e03b189246691de08846ab0f9b
Cr-Commit-Position: refs/heads/master@{#422835}

[fdoray, 2016-10-03 21:27:34]

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

[commit-bot: I haz the power, 2016-10-03 21:28:32]

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, 2016-10-03 21:47:49]

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

[commit-bot: I haz the power, 2016-10-03 21:47:49]

Dry run: Try jobs failed on following builders:
  chromeos_daisy_chromium_compile_only_ng on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromeos_daisy_...)
  chromeos_x86-generic_chromium_compile_only_ng on
master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromeos_x86-ge...)

[fdoray, 2016-10-04 13:21:12]

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

[commit-bot: I haz the power, 2016-10-04 13:21:27]

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, 2016-10-04 14:03:14]

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

[commit-bot: I haz the power, 2016-10-04 14:03:15]

Dry run: This issue passed the CQ dry run.

[fdoray, 2016-10-04 15:00:25]

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

[fdoray, 2016-10-04 15:00:26]

PTAL

[tbarzic, 2016-10-04 16:37:58]

lgtm

[fdoray, 2016-10-04 17:07:07]

The CQ bit was checked by fdoray@chromium.org

[commit-bot: I haz the power, 2016-10-04 17:07:47]

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, 2016-10-04 17:13:48]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-10-04 17:16:32]

Description was changed from

==========
Use FileDescriptorWatcher in ProcessOutputWatcher

This allows ProcessOutputWatcher to be used from any thread that
instantiates a FileDescriptorWatcher (not just threads that run
a MessageLoopForIO). This will facilitate the migration of
BrowserThreads to base/task_scheduler.

BUG=645114
==========

to

==========
Use FileDescriptorWatcher in ProcessOutputWatcher

This allows ProcessOutputWatcher to be used from any thread that
instantiates a FileDescriptorWatcher (not just threads that run
a MessageLoopForIO). This will facilitate the migration of
BrowserThreads to base/task_scheduler.

BUG=645114

Committed: https://crrev.com/0bd9f1a1ba8ea5e03b189246691de08846ab0f9b
Cr-Commit-Position: refs/heads/master@{#422835}
==========

[commit-bot: I haz the power, 2016-10-04 17:16:33]

Patchset 2 (id:??) landed as
https://crrev.com/0bd9f1a1ba8ea5e03b189246691de08846ab0f9b
Cr-Commit-Position: refs/heads/master@{#422835}