Unify locks in TaskQueueImpl

We no longer need to split the lock in TaskQueueImpl.

Change-Id: I05d1bc597f34fbe4a1a10ffc3a95fc451b72abc6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1504017
Commit-Queue: Alex Clarke <alexclarke@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638068}
2 files changed