Allow cross-thread destruction of RTCStatsRequest objects.

Allow cross-thread destruction of RTCStatsRequest objects.

libjingle threads may in some cases end up finalizing WebRTCStatsRequest
objects, deref'ing such objects last via LocalRTCStatsRequest.

To allow such cross-thread release of the underlying Blink object,
annotate WebRTCStatsRequest's private pointer as cross-thread destructible.

R=
BUG=541762
Committed: https://crrev.com/ded5273e5572ce8fc7e9871a61ced4e12282681f
Cr-Commit-Position: refs/heads/master@{#353642}

[sof, 2015-10-11 06:51:30]

sigbjornf@opera.com changed reviewers:
+ haraken@chromium.org, tkent@chromium.org

[sof, 2015-10-11 06:51:30]

please take a look.

unable to reproduce locally, but the crash report is clear enough wrt crash
cause.

[haraken, 2015-10-11 07:53:36]

LGTM

[sof, 2015-10-11 16:06:12]

On 2015/10/11 07:53:36, haraken wrote:
> LGTM

Thanks (needs public/ approval).

LocalRTCStatsResponse does not require the same treatment, as it is created &
destructed on the main thread.

[tkent, 2015-10-12 23:09:43]

The CQ bit was checked by tkent@chromium.org

[tkent, 2015-10-12 23:09:44]

lgtm

[commit-bot: I haz the power, 2015-10-12 23:10:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1399903002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1399903002/1

[commit-bot: I haz the power, 2015-10-13 00:34:29]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-13 00:35:21]

Patchset 1 (id:??) landed as
https://crrev.com/ded5273e5572ce8fc7e9871a61ced4e12282681f
Cr-Commit-Position: refs/heads/master@{#353642}