Cast: Avoid hitting a DCHECK caused by race condition

Cast: Avoid hitting a DCHECK caused by race condition

RTCP sender report has a race condition when then current time is
submitted asynchronously (from another process). This caused the value
for DLRR to be negative.

This code is going to be removed it is fine to just suppress this
condition.

BUG=393042
NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=284521

[Alpha Left Google, 2014-07-21 18:07:38]

The CQ bit was checked by hclam@chromium.org

[commit-bot: I haz the power, 2014-07-21 18:09:06]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/hclam@chromium.org/410433002/20001

[commit-bot: I haz the power, 2014-07-21 20:04:10]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)
  win_chromium_x64_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_x64_rel/...)
  win_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu/builds/35508)

[commit-bot: I haz the power, 2014-07-21 20:06:58]

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

[commit-bot: I haz the power, 2014-07-21 20:06:59]

Try jobs failed on following builders:
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)

[miu, 2014-07-21 21:21:19]

lgtm

[miu, 2014-07-21 21:21:29]

The CQ bit was unchecked by miu@chromium.org

[miu, 2014-07-21 21:22:03]

The CQ bit was checked by miu@chromium.org

[miu, 2014-07-21 21:22:51]

On 2014/07/21 21:22:03, miu wrote:
> The CQ bit was checked by mailto:miu@chromium.org

Submitting w/ NOTRY=true since this issue is flakily closing the tree, so it
should commit ASAP.

[commit-bot: I haz the power, 2014-07-21 21:23:11]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/hclam@chromium.org/410433002/20001

[commit-bot: I haz the power, 2014-07-21 22:38:05]

Change committed as 284521