Add PRESUBMIT tests for _CheckUserActionUpdate function.

Add PRESUBMIT tests for _CheckUserActionUpdate function.

Presubmit does not contain any tests for the _CheckUserActionUpdate
function. This commit adds a test to check against an action in
actions.xml and one that is not found there. To do this we have to
improve the MockInputApi and MockFile classes.

BUG=462814
Committed: https://crrev.com/e0426257f867edcef07a156152c61ac01c490dda
Cr-Commit-Position: refs/heads/master@{#318759}

[davileen, 2015-02-28 01:33:12]

davileen@amazon.com changed reviewers:
+ phajdan.jr@chromium.org

[davileen, 2015-02-28 01:35:06]

Hi Pawel,

Here's a proposed fix for
https://code.google.com/p/chromium/issues/detail?id=462814

PTAL,
Thanks David

[Paweł Hajdan Jr., 2015-03-02 19:41:45]

LGTM

[davileen, 2015-03-02 19:43:07]

The CQ bit was checked by davileen@amazon.com

[commit-bot: I haz the power, 2015-03-02 19:55:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/966703003/1

[commit-bot: I haz the power, 2015-03-02 21:10:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-02 21:12:20]

Patchset 1 (id:??) landed as
https://crrev.com/e0426257f867edcef07a156152c61ac01c490dda
Cr-Commit-Position: refs/heads/master@{#318759}

[brucedawson, 2015-06-29 23:01:17]

This seems to be causing presubmit failures. See comment on bug.