Revert of [Sync] Refactor ModelSafeWorker::DoWorkAndWaitUntilDone() to avoid code duplication.

Revert of [Sync] Refactor ModelSafeWorker::DoWorkAndWaitUntilDone() to avoid code duplication. (patchset #11 id:200001 of https://codereview.chromium.org/2782573002/ )

Reason for revert:
Causing build failure. More info at https://bugs.chromium.org/p/chromium/issues/detail?id=711466.

Original issue's description:
> [Sync] Refactor ModelSafeWorker::DoWorkAndWaitUntilDone() to avoid code duplication.
> 
> Before this CL, logic to wait for a WorkCallback to run or be
> abandoned was duplicated in multiple
> ModelSafeWorker::DoWorkAndWaitUntilDoneImpl() implementations.
> 
> With this CL, ModelSafeWorker::DoWorkAndWaitUntilDoneImpl() is
> replaced with ModelSafeWorker::ScheduleWork(). Implementations
> are merely responsible for scheduling the callback that they
> receive; they don't have to wait for it to run or be abandoned.
> 
> The logic to wait for the callback to run or be abandoned is moved
> into ModelSafeWorker::DoWorkAndWaitUntilDone().
> ModelSafeWorker::DoWorkAndWaitUntilDone() calls
> ModelSafeWorker::ScheduleWork(). Then, it waits until either the
> callback that it passed to ModelSafeWorker::ScheduleWork() is deleted
> (may or may not have run) or ModelSafeWorker::RequestStop() is called
> before the callback has started to run. Additionnaly, calling
> ModelSafeWorker::RequestStop() transforms into no-op further
> invocations of callbacks passed to ModelSafeWorker::ScheduleWork().
> 
> Unblocking ModelSafeWorker::DoWorkAndWaitUntilDone() when
> ModelSafeWorker::RequestStop() is called is important to
> prevent deadlocks in workers that schedule work on the UI
> thread. Indeed, in Chrome, no tasks are scheduled on the UI
> thread after ModelSafeWorker::RequestStop() is called and
> pending UI tasks are not scheduled until after the sync thread
> is joined.
> 
> BUG=663600
> 
> Review-Url: https://codereview.chromium.org/2782573002
> Cr-Commit-Position: refs/heads/master@{#463413}
> Committed: https://chromium.googlesource.com/chromium/src/+/316c08f3692150ac1c416c67391768622cc6a77f

TBR=brettw@chromium.org,skym@chromium.org,dvadym@chromium.org,fdoray@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=663600
Review-Url: https://codereview.chromium.org/2820623002
Cr-Commit-Position: refs/heads/master@{#464628}
Committed: https://chromium.googlesource.com/chromium/src/+/bb76b686d4b7ed1fd7413a1f4ee17de4452d1ac0

[cmumford, 2017-04-13 23:00:49]

The CQ bit was checked by cmumford@chromium.org

[cmumford, 2017-04-13 23:00:49]

Created Revert of [Sync] Refactor ModelSafeWorker::DoWorkAndWaitUntilDone() to
avoid code duplication.

[commit-bot: I haz the power, 2017-04-13 23:01:41]

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, 2017-04-14 00:38:37]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1492124449579950, "parent_rev":
"2e5a5b8efccf655f183cc7ce0c59a88f77bb50f5", "commit_rev":
"bb76b686d4b7ed1fd7413a1f4ee17de4452d1ac0"}

[commit-bot: I haz the power, 2017-04-14 00:39:32]

Description was changed from

==========
Revert of [Sync] Refactor ModelSafeWorker::DoWorkAndWaitUntilDone() to avoid
code duplication. (patchset #11 id:200001 of
https://codereview.chromium.org/2782573002/ )

Reason for revert:
Causing build failure. More info at
https://bugs.chromium.org/p/chromium/issues/detail?id=711466.

Original issue's description:
> [Sync] Refactor ModelSafeWorker::DoWorkAndWaitUntilDone() to avoid code
duplication.
> 
> Before this CL, logic to wait for a WorkCallback to run or be
> abandoned was duplicated in multiple
> ModelSafeWorker::DoWorkAndWaitUntilDoneImpl() implementations.
> 
> With this CL, ModelSafeWorker::DoWorkAndWaitUntilDoneImpl() is
> replaced with ModelSafeWorker::ScheduleWork(). Implementations
> are merely responsible for scheduling the callback that they
> receive; they don't have to wait for it to run or be abandoned.
> 
> The logic to wait for the callback to run or be abandoned is moved
> into ModelSafeWorker::DoWorkAndWaitUntilDone().
> ModelSafeWorker::DoWorkAndWaitUntilDone() calls
> ModelSafeWorker::ScheduleWork(). Then, it waits until either the
> callback that it passed to ModelSafeWorker::ScheduleWork() is deleted
> (may or may not have run) or ModelSafeWorker::RequestStop() is called
> before the callback has started to run. Additionnaly, calling
> ModelSafeWorker::RequestStop() transforms into no-op further
> invocations of callbacks passed to ModelSafeWorker::ScheduleWork().
> 
> Unblocking ModelSafeWorker::DoWorkAndWaitUntilDone() when
> ModelSafeWorker::RequestStop() is called is important to
> prevent deadlocks in workers that schedule work on the UI
> thread. Indeed, in Chrome, no tasks are scheduled on the UI
> thread after ModelSafeWorker::RequestStop() is called and
> pending UI tasks are not scheduled until after the sync thread
> is joined.
> 
> BUG=663600
> 
> Review-Url: https://codereview.chromium.org/2782573002
> Cr-Commit-Position: refs/heads/master@{#463413}
> Committed:
https://chromium.googlesource.com/chromium/src/+/316c08f3692150ac1c416c673917...

TBR=brettw@chromium.org,skym@chromium.org,dvadym@chromium.org,fdoray@chromium...
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=663600
==========

to

==========
Revert of [Sync] Refactor ModelSafeWorker::DoWorkAndWaitUntilDone() to avoid
code duplication. (patchset #11 id:200001 of
https://codereview.chromium.org/2782573002/ )

Reason for revert:
Causing build failure. More info at
https://bugs.chromium.org/p/chromium/issues/detail?id=711466.

Original issue's description:
> [Sync] Refactor ModelSafeWorker::DoWorkAndWaitUntilDone() to avoid code
duplication.
> 
> Before this CL, logic to wait for a WorkCallback to run or be
> abandoned was duplicated in multiple
> ModelSafeWorker::DoWorkAndWaitUntilDoneImpl() implementations.
> 
> With this CL, ModelSafeWorker::DoWorkAndWaitUntilDoneImpl() is
> replaced with ModelSafeWorker::ScheduleWork(). Implementations
> are merely responsible for scheduling the callback that they
> receive; they don't have to wait for it to run or be abandoned.
> 
> The logic to wait for the callback to run or be abandoned is moved
> into ModelSafeWorker::DoWorkAndWaitUntilDone().
> ModelSafeWorker::DoWorkAndWaitUntilDone() calls
> ModelSafeWorker::ScheduleWork(). Then, it waits until either the
> callback that it passed to ModelSafeWorker::ScheduleWork() is deleted
> (may or may not have run) or ModelSafeWorker::RequestStop() is called
> before the callback has started to run. Additionnaly, calling
> ModelSafeWorker::RequestStop() transforms into no-op further
> invocations of callbacks passed to ModelSafeWorker::ScheduleWork().
> 
> Unblocking ModelSafeWorker::DoWorkAndWaitUntilDone() when
> ModelSafeWorker::RequestStop() is called is important to
> prevent deadlocks in workers that schedule work on the UI
> thread. Indeed, in Chrome, no tasks are scheduled on the UI
> thread after ModelSafeWorker::RequestStop() is called and
> pending UI tasks are not scheduled until after the sync thread
> is joined.
> 
> BUG=663600
> 
> Review-Url: https://codereview.chromium.org/2782573002
> Cr-Commit-Position: refs/heads/master@{#463413}
> Committed:
https://chromium.googlesource.com/chromium/src/+/316c08f3692150ac1c416c673917...

TBR=brettw@chromium.org,skym@chromium.org,dvadym@chromium.org,fdoray@chromium...
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=663600

Review-Url: https://codereview.chromium.org/2820623002
Cr-Commit-Position: refs/heads/master@{#464628}
Committed:
https://chromium.googlesource.com/chromium/src/+/bb76b686d4b7ed1fd7413a1f4ee1...
==========

[commit-bot: I haz the power, 2017-04-14 00:39:33]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/bb76b686d4b7ed1fd7413a1f4ee1...