Make sure Blink WebRTCSessionDescriptionRequest and WebRTCVoidRequest are deleted on the correct th…

Make sure Blink WebRTCSessionDescriptionRequest and WebRTCVoidRequest are deleted on the correct thread in RTCPeerConnectionHandler.
Blink objects must always be destroyed on the main render thread. Since the object holding WebRTCSessionDescriptionRequest and WebRTCVoidRequest in rtc_peerconnection_handler.cc are refcounted, the destructor is not ensured to run on the main render thread.

BUG=470047
Committed: https://crrev.com/44acfec4479754f0314e16251af45bb9453e0ba8
Cr-Commit-Position: refs/heads/master@{#321989}

[perkj_chrome, 2015-03-24 10:59:08]

perkj@chromium.org changed reviewers:
+ tommi@chromium.org

[perkj_chrome, 2015-03-24 10:59:09]

please

[tommi (sloooow) - chröme, 2015-03-24 12:29:09]

The CQ bit was checked by tommi@chromium.org

[tommi (sloooow) - chröme, 2015-03-24 12:29:09]

lgtm

[commit-bot: I haz the power, 2015-03-24 12:29:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1023443007/1

[commit-bot: I haz the power, 2015-03-24 13:29:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-24 13:29:52]

Patchset 1 (id:??) landed as
https://crrev.com/44acfec4479754f0314e16251af45bb9453e0ba8
Cr-Commit-Position: refs/heads/master@{#321989}