Update LocationLine without IO.

Update LocationLine without IO.

This enables to update location line even when IO is busy for other operation,
e.g. directory rescan.

BUG=460405
TEST=manually tested. Navigate to a directory and see how the UI changes.

Committed: https://crrev.com/8c4c9c38c0caa2ab880b293c46d0429d99dd6d27
Cr-Commit-Position: refs/heads/master@{#317539}

[yawano, 2015-02-20 12:30:31]

yawano@chromium.org changed reviewers:
+ fukino@chromium.org

[yawano, 2015-02-20 12:30:31]

PTAL. Thank you!

[fukino, 2015-02-20 13:31:26]

lgtm. Thank you!

[yawano, 2015-02-23 01:25:46]

The CQ bit was checked by yawano@chromium.org

[commit-bot: I haz the power, 2015-02-23 01:25:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/946543002/1

[commit-bot: I haz the power, 2015-02-23 01:28:45]

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

[commit-bot: I haz the power, 2015-02-23 01:28:46]

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

[yawano, 2015-02-23 01:57:23]

New patchsets have been uploaded after l-g-t-m from fukino@chromium.org

[yawano, 2015-02-23 03:35:54]

The CQ bit was checked by yawano@chromium.org

[commit-bot: I haz the power, 2015-02-23 03:36:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/946543002/20001

[commit-bot: I haz the power, 2015-02-23 03:38:50]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-02-23 03:39:25]

Patchset 2 (id:??) landed as
https://crrev.com/8c4c9c38c0caa2ab880b293c46d0429d99dd6d27
Cr-Commit-Position: refs/heads/master@{#317539}