Handle incoming frames with the same timestamp.

Handle incoming frames with the same timestamp.

Crash analysis shows frames with the same timestamp getting through.

Replaces the old frame if the old frame hasn't yet been rendered or
drops the new frame if the old frame has already been shown.

BUG=485042
TEST=new unittest.

Committed: https://crrev.com/fd4edb8ffe11baf94d554e923b23ca9caefe2d03
Cr-Commit-Position: refs/heads/master@{#328693}

[DaleCurtis, 2015-05-06 23:08:08]

Patchset #1 (id:1) has been deleted

[DaleCurtis, 2015-05-06 23:08:20]

dalecurtis@chromium.org changed reviewers:
+ xhwang@chromium.org

[xhwang, 2015-05-07 00:32:25]

lgtm

[DaleCurtis, 2015-05-07 00:35:12]

Thanks for review :)

[DaleCurtis, 2015-05-07 00:35:16]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2015-05-07 00:36:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1126413002/20001

[commit-bot: I haz the power, 2015-05-07 03:42:56]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-05-07 03:43:47]

Patchset 1 (id:??) landed as
https://crrev.com/fd4edb8ffe11baf94d554e923b23ca9caefe2d03
Cr-Commit-Position: refs/heads/master@{#328693}