Use FileDescriptorWatcher in AlarmTimer.

Use FileDescriptorWatcher in AlarmTimer.

This CL is identical to https://codereview.chromium.org/2398753003/
which was reverted % fixes to avoid memory leaks in tests.

FileDescriptorWatcher is a new API that replaces
MessageLoopForIO::WatchFileDescriptor.

This CL also gets rid of the base::Thread created in the anonymous
namespace of alarm_timer_chromeos.cc. The FileDescriptorWatcher
API is supported by every TaskScheduler thread. Very soon, most
tasks in Chrome will run in TaskScheduler. Therefore, there is no
reason to create a base::Thread to allow AlarmTimer to be used from
threads that don't support the FileDescriptorWatcher API.

BUG=645114
Committed: https://crrev.com/51dbb9577b6a8194f025d790f581c10559f3ee2a
Cr-Commit-Position: refs/heads/master@{#424471}

[fdoray, 2016-10-07 16:03:04]

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

[commit-bot: I haz the power, 2016-10-07 16:03:24]

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

[fdoray, 2016-10-07 16:03:28]

The CQ bit was unchecked by fdoray@chromium.org

[fdoray, 2016-10-07 16:04:42]

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

[commit-bot: I haz the power, 2016-10-07 16:04:56]

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, 2016-10-07 16:30:31]

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

[commit-bot: I haz the power, 2016-10-07 16:30:32]

Dry run: This issue passed the CQ dry run.

[fdoray, 2016-10-07 20:38:17]

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

[commit-bot: I haz the power, 2016-10-07 20:38:50]

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, 2016-10-07 21:13:38]

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

[commit-bot: I haz the power, 2016-10-07 21:13:39]

Dry run: This issue passed the CQ dry run.

[fdoray, 2016-10-11 12:35:29]

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

[fdoray, 2016-10-11 12:35:30]

PTAL

[Chirantan Ekbote, 2016-10-11 16:43:54]

lgtm

[fdoray, 2016-10-11 17:04:31]

The CQ bit was checked by fdoray@chromium.org

[commit-bot: I haz the power, 2016-10-11 17:04:43]

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 17:33:59]

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

[commit-bot: I haz the power, 2016-10-11 17:34:02]

Failed to apply the patch.
On branch working_branch
Your branch is up-to-date with 'origin/refs/pending/heads/master'.
nothing to commit, working tree clean

[commit-bot: I haz the power, 2016-10-11 17:34:58]

Description was changed from

==========
Use FileDescriptorWatcher in AlarmTimer.

This CL is identical to https://codereview.chromium.org/2398753003/
which was reverted % fixes to avoid memory leaks in tests.

FileDescriptorWatcher is a new API that replaces
MessageLoopForIO::WatchFileDescriptor.

This CL also gets rid of the base::Thread created in the anonymous
namespace of alarm_timer_chromeos.cc. The FileDescriptorWatcher
API is supported by every TaskScheduler thread. Very soon, most
tasks in Chrome will run in TaskScheduler. Therefore, there is no
reason to create a base::Thread to allow AlarmTimer to be used from
threads that don't support the FileDescriptorWatcher API.

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

to

==========
Use FileDescriptorWatcher in AlarmTimer.

This CL is identical to https://codereview.chromium.org/2398753003/
which was reverted % fixes to avoid memory leaks in tests.

FileDescriptorWatcher is a new API that replaces
MessageLoopForIO::WatchFileDescriptor.

This CL also gets rid of the base::Thread created in the anonymous
namespace of alarm_timer_chromeos.cc. The FileDescriptorWatcher
API is supported by every TaskScheduler thread. Very soon, most
tasks in Chrome will run in TaskScheduler. Therefore, there is no
reason to create a base::Thread to allow AlarmTimer to be used from
threads that don't support the FileDescriptorWatcher API.

BUG=645114

Committed: https://crrev.com/51dbb9577b6a8194f025d790f581c10559f3ee2a
Cr-Commit-Position: refs/heads/master@{#424471}
==========

[commit-bot: I haz the power, 2016-10-11 17:34:59]

Patchset 3 (id:??) landed as
https://crrev.com/51dbb9577b6a8194f025d790f581c10559f3ee2a
Cr-Commit-Position: refs/heads/master@{#424471}