GpuMain: Fix thread_runner() access DCHECK fail

GpuMain: Fix thread_runner() access DCHECK fail

Accessing base::Thread::task_runner() on an arbitrary thread is unsafe.
This causes a DCHECK to fail on some mus_ws_unittests. This CL saves
the task runner for the gpu thread and the compositor thread in member
variables to ensure safe access to the task runners.

BUG=none

Review-Url: https://codereview.chromium.org/2736693003
Cr-Commit-Position: refs/heads/master@{#454891}
Committed: https://chromium.googlesource.com/chromium/src/+/cd2a7b5cf2df1b844fd3894d2d0d5410406fe3ab

[Fady Samuel, 2017-03-06 16:58:55]

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

[Fady Samuel, 2017-03-06 16:59:05]

fsamuel@chromium.org changed reviewers:
+ sadrul@chromium.org

[commit-bot: I haz the power, 2017-03-06 16:59:18]

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, 2017-03-06 17:56:52]

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

[commit-bot: I haz the power, 2017-03-06 17:56:53]

Dry run: This issue passed the CQ dry run.

[sadrul, 2017-03-06 18:11:32]

lgtm

[Fady Samuel, 2017-03-06 18:11:50]

The CQ bit was checked by fsamuel@chromium.org

[commit-bot: I haz the power, 2017-03-06 18:12:11]

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, 2017-03-06 18:24:18]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1488823910103110, "parent_rev":
"399f2e5e66b0ab059852ac7f1e82f334640c3b38", "commit_rev":
"cd2a7b5cf2df1b844fd3894d2d0d5410406fe3ab"}

[commit-bot: I haz the power, 2017-03-06 18:24:54]

Description was changed from

==========
GpuMain: Fix thread_runner() access DCHECK fail

Accessing base::Thread::task_runner() on an arbitrary thread is unsafe.
This causes a DCHECK to fail on some mus_ws_unittests. This CL saves
the task runner for the gpu thread and the compositor thread in member
variables to ensure safe access to the task runners.

BUG=none
==========

to

==========
GpuMain: Fix thread_runner() access DCHECK fail

Accessing base::Thread::task_runner() on an arbitrary thread is unsafe.
This causes a DCHECK to fail on some mus_ws_unittests. This CL saves
the task runner for the gpu thread and the compositor thread in member
variables to ensure safe access to the task runners.

BUG=none

Review-Url: https://codereview.chromium.org/2736693003
Cr-Commit-Position: refs/heads/master@{#454891}
Committed:
https://chromium.googlesource.com/chromium/src/+/cd2a7b5cf2df1b844fd3894d2d0d...
==========

[commit-bot: I haz the power, 2017-03-06 18:24:55]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/cd2a7b5cf2df1b844fd3894d2d0d...