[Merge to M53] Worker: Remove locking from WorkerThread::postTask()

[Merge to M53] Worker: Remove locking from WorkerThread::postTask()

WorkerThread::postTask() can be called from various places and locking in the
function may lead to deadlock. To avoid the problem, this CL removes locking
from WorkerThread::postTask() and makes it possible to safely access to shared
flags without locking.

BUG=620442
Review-Url: https://codereview.chromium.org/2142273004
Cr-Commit-Position: refs/heads/master@{#405715}
(cherry picked from commit 18d1be3c48e503e5d080361f8fe6df7cfd2b503e)

Committed: https://chromium.googlesource.com/chromium/src/+/b70891a44868d73034b78417cad991307819e5a5

[nhiroki, 2016-07-20 01:45:34]

Description was changed from

==========
[Merge to M53] Worker: Remove locking from WorkerThread::postTask()

WorkerThread::postTask() can be called from various places and locking in the
function may lead to deadlock. To avoid the problem, this CL removes locking
from WorkerThread::postTask() and makes it possible to safely access to shared
flags without locking.

BUG=620442

Review-Url: https://codereview.chromium.org/2142273004
Cr-Commit-Position: refs/heads/master@{#405715}
(cherry picked from commit 18d1be3c48e503e5d080361f8fe6df7cfd2b503e)
==========

to

==========
[Merge to M53] Worker: Remove locking from WorkerThread::postTask()

WorkerThread::postTask() can be called from various places and locking in the
function may lead to deadlock. To avoid the problem, this CL removes locking
from WorkerThread::postTask() and makes it possible to safely access to shared
flags without locking.

BUG=620442

Review-Url: https://codereview.chromium.org/2142273004
Cr-Commit-Position: refs/heads/master@{#405715}
(cherry picked from commit 18d1be3c48e503e5d080361f8fe6df7cfd2b503e)

Committed:
https://chromium.googlesource.com/chromium/src/+/b70891a44868d73034b78417cad9...
==========

[nhiroki, 2016-07-20 01:45:36]

Committed patchset #1 (id:1) manually as
b70891a44868d73034b78417cad991307819e5a5.