Fix race when reloading original URL.

Fix race when reloading original URL.

Fixes an issue where the browser's last committed entry and the renderer can become out of sync when reloading the original requested URL, which causes the browser to kill the renderer process.

BUG=491861
TBR=creis@chromium.org
NOTRY=true
NOPRESUBMIT=true

Review URL: https://codereview.chromium.org/1189413005

Cr-Commit-Position: refs/heads/master@{#338864}
(cherry picked from commit 573e8be6d639b7066a270ae99d02e829e10b90dd)

[lfg, 2015-07-28 15:18:02]

lfg@chromium.org changed reviewers:
+ creis@chromium.org
- jam@chromium.org for chromium.fyi.json

[lfg, 2015-07-28 15:19:08]

The CQ bit was checked by lfg@chromium.org

[commit-bot: I haz the power, 2015-07-28 15:19:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1255103003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1255103003/1

[commit-bot: I haz the power, 2015-07-28 15:19:22]

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

[commit-bot: I haz the power, 2015-07-28 15:19:23]

CLs for remote refs other than refs/pending/heads/master must contain NOTRY=true
and NOPRESUBMIT=true in order for the CQ to process them

[lfg, 2015-07-28 15:21:34]

The CQ bit was checked by lfg@chromium.org

[commit-bot: I haz the power, 2015-07-28 15:21:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1255103003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1255103003/1

[commit-bot: I haz the power, 2015-07-28 15:23:15]

Committed patchset #1 (id:1)