Revert of Always post buffering state updates since they may change sink state.

Revert of Always post buffering state updates since they may change sink state. (patchset #1 id:1 of https://codereview.chromium.org/1161463006/)

Reason for revert:
Speculative revert for Blink layout tests crashes on Nexus 4:
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Android%20%28Nexus4%29
(SEGV on CrGpuMain thread is observed)

Sorry if my guess is not correct; there wasn't
a clear signal to identify the culprit.

Original issue's description:
> Always post buffering state updates since they may change sink state.
>
> The lock must never be held when OnTimeStateChanged() is calling into
> the VideoRendererSink or we can deadlock the compositor thread.
>
> With video-only playback occurs a buffering state change for underflow
> would immediately invoke OnTimeStateChanged(false) which would try to
> stop the VideoRendererSink under lock.
>
> BUG=496466
> TEST=video only playback doesn't deadlock.
>
> Committed: https://crrev.com/9d8a53f3bf01aed28abbd1f9a713a25362c0d158
> Cr-Commit-Position: refs/heads/master@{#332772}

TBR=xhwang@chromium.org,dalecurtis@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=496466
Committed: https://crrev.com/9fc2a61ce37405635c5528db9d5773c4f30b592d
Cr-Commit-Position: refs/heads/master@{#332808}

[Yuta Kitamura, 2015-06-04 09:41:39]

Created Revert of Always post buffering state updates since they may change sink
state.

[commit-bot: I haz the power, 2015-06-04 09:42:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1159573005/1

[commit-bot: I haz the power, 2015-06-04 09:42:45]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-04 09:43:29]

Patchset 1 (id:??) landed as
https://crrev.com/9fc2a61ce37405635c5528db9d5773c4f30b592d
Cr-Commit-Position: refs/heads/master@{#332808}

[Yuta Kitamura, 2015-06-04 10:43:12]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1157573009/ by yutak@chromium.org.

The reason for reverting is: The original patch was innocent..