Ensure GpuVideoDecoder satisfies outstanding reads before firing callback indicating it is reset.

Ensure GpuVideoDecoder satisfies outstanding reads before firing callback indicating it is reset.

Previously GVD would post the fake frame to VideoRendererBase, but fire the
callback without waiting for VRB to process the frame.  Now the callback is
posted to the same loop so VRB is guaranteed to see the frame before
VRB::OnDecoderFlushDone() DCHECKs that !pending_read_.

TEST=closing a tab playing HW-accelerated video no longer DCHECKs in VRB::OnDecoderFlushDone.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=141746

[Ami GONE FROM CHROMIUM, 2012-06-12 18:21:43]

acolwell: please review.
posciak: FYI.

[acolwell GONE FROM CHROMIUM, 2012-06-12 20:17:00]

LGTM

[commit-bot: I haz the power, 2012-06-12 20:19:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/fischman@chromium.org/10536122/1

[commit-bot: I haz the power, 2012-06-12 21:46:13]

Change committed as 141746