Revert of Remove MessageLoop::current() from base::win::ObjectWatcher.

Revert of Remove MessageLoop::current() from base::win::ObjectWatcher. (patchset #5 id:80001 of https://codereview.chromium.org/2125763003/ )

Reason for revert:
Breaks Win10 builder. crbug.com/632184

Original issue's description:
> Remove MessageLoop::current() from base::win::ObjectWatcher.
>
> Why? The fact that there's a MessageLoop on the thread is an
> unnecessary implementation detail. When browser threads are migrated to
> base/task_scheduler, tasks will no longer have access to a MessageLoop
> but they will be able to get the current ThreadTaskRunnerHandle.
>
> Before this CL, ObjectWatcher implemented
> WillDestroyCurrentMessageLoop() to stop the watch when the
> MessageLoop responsible for running the callback was destroyed.
> This prevented the watch callback from being sent to a destroyed
> MessageLoop.
>
> Now that ObjectWatcher keeps a reference to a TaskRunner, this is
> no longer required. The TaskRunner can't be deleted while there are
> references to it. If the underlying MessageLoop has been deleted
> when the watch callback is posted, the callback will simply not run.
>
> Note that the watch will still be stopped when the ObjectWatcher is
> deleted.
>
> TBR=ben@chromium.org
> BUG=616447
>
> Committed: https://crrev.com/76db1513714741d8d6e6dd6e872d50f20b090fce
> Cr-Commit-Position: refs/heads/master@{#407874}

TBR=grt@chromium.org,ben@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=616447
Committed: https://crrev.com/00108e0c668b75d9416d50852176ce39c5454e2d
Cr-Commit-Position: refs/heads/master@{#414465}

[fdoray, 2016-08-25 16:14:02]

The CQ bit was checked by fdoray@chromium.org

[fdoray, 2016-08-25 16:14:03]

Created Revert of Remove MessageLoop::current() from base::win::ObjectWatcher.

[commit-bot: I haz the power, 2016-08-25 16:14:38]

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, 2016-08-25 17:33:53]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-25 17:35:55]

Description was changed from

==========
Revert of Remove MessageLoop::current() from base::win::ObjectWatcher. (patchset
#5 id:80001 of https://codereview.chromium.org/2125763003/ )

Reason for revert:
Breaks Win10 builder. crbug.com/632184

Original issue's description:
> Remove MessageLoop::current() from base::win::ObjectWatcher.
> 
> Why? The fact that there's a MessageLoop on the thread is an
> unnecessary implementation detail. When browser threads are migrated to
> base/task_scheduler, tasks will no longer have access to a MessageLoop
> but they will be able to get the current ThreadTaskRunnerHandle.
> 
> Before this CL, ObjectWatcher implemented
> WillDestroyCurrentMessageLoop() to stop the watch when the
> MessageLoop responsible for running the callback was destroyed.
> This prevented the watch callback from being sent to a destroyed
> MessageLoop.
> 
> Now that ObjectWatcher keeps a reference to a TaskRunner, this is
> no longer required. The TaskRunner can't be deleted while there are
> references to it. If the underlying MessageLoop has been deleted
> when the watch callback is posted, the callback will simply not run.
> 
> Note that the watch will still be stopped when the ObjectWatcher is
> deleted.
> 
> TBR=ben@chromium.org
> BUG=616447
> 
> Committed: https://crrev.com/76db1513714741d8d6e6dd6e872d50f20b090fce
> Cr-Commit-Position: refs/heads/master@{#407874}

TBR=grt@chromium.org,ben@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=616447
==========

to

==========
Revert of Remove MessageLoop::current() from base::win::ObjectWatcher. (patchset
#5 id:80001 of https://codereview.chromium.org/2125763003/ )

Reason for revert:
Breaks Win10 builder. crbug.com/632184

Original issue's description:
> Remove MessageLoop::current() from base::win::ObjectWatcher.
>
> Why? The fact that there's a MessageLoop on the thread is an
> unnecessary implementation detail. When browser threads are migrated to
> base/task_scheduler, tasks will no longer have access to a MessageLoop
> but they will be able to get the current ThreadTaskRunnerHandle.
>
> Before this CL, ObjectWatcher implemented
> WillDestroyCurrentMessageLoop() to stop the watch when the
> MessageLoop responsible for running the callback was destroyed.
> This prevented the watch callback from being sent to a destroyed
> MessageLoop.
>
> Now that ObjectWatcher keeps a reference to a TaskRunner, this is
> no longer required. The TaskRunner can't be deleted while there are
> references to it. If the underlying MessageLoop has been deleted
> when the watch callback is posted, the callback will simply not run.
>
> Note that the watch will still be stopped when the ObjectWatcher is
> deleted.
>
> TBR=ben@chromium.org
> BUG=616447
>
> Committed: https://crrev.com/76db1513714741d8d6e6dd6e872d50f20b090fce
> Cr-Commit-Position: refs/heads/master@{#407874}

TBR=grt@chromium.org,ben@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=616447

Committed: https://crrev.com/00108e0c668b75d9416d50852176ce39c5454e2d
Cr-Commit-Position: refs/heads/master@{#414465}
==========

[commit-bot: I haz the power, 2016-08-25 17:35:56]

Patchset 1 (id:??) landed as
https://crrev.com/00108e0c668b75d9416d50852176ce39c5454e2d
Cr-Commit-Position: refs/heads/master@{#414465}