Fix output surface Memory Dump Provider unregistration.

Fix output surface Memory Dump Provider unregistration.

The memory dump provider for OutputSurface was registered on the
client thread, but could be unregistered on the main thread in cases when
the client was cleaned up before the destructor was called (very common).
Move the unregistration code to the parallel of the registration code, so that
both only when appropriate, on the client thread.

BUG=536824
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/1fd62112fb543ccf8fe9af896cf09142ad06c4ec
Cr-Commit-Position: refs/heads/master@{#351176}

[ericrk, 2015-09-28 17:54:00]

ericrk@chromium.org changed reviewers:
+ primiano@chromium.org, reveman@chromium.org

[reveman, 2015-09-28 18:04:13]

lgtm

[ericrk, 2015-09-28 18:12:37]

The CQ bit was checked by ericrk@chromium.org

[commit-bot: I haz the power, 2015-09-28 18:13:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1371163002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1371163002/1

[commit-bot: I haz the power, 2015-09-28 20:17:42]

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

[commit-bot: I haz the power, 2015-09-28 20:17:42]

Try jobs failed on following builders:
  win_chromium_compile_dbg_ng on tryserver.chromium.win (JOB_TIMED_OUT, no build
URL)

[ericrk, 2015-09-28 21:48:28]

The CQ bit was checked by ericrk@chromium.org

[commit-bot: I haz the power, 2015-09-28 21:52:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1371163002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1371163002/1

[commit-bot: I haz the power, 2015-09-28 22:39:33]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-28 22:40:34]

Patchset 1 (id:??) landed as
https://crrev.com/1fd62112fb543ccf8fe9af896cf09142ad06c4ec
Cr-Commit-Position: refs/heads/master@{#351176}