Add sharing flag to file open during unsafe image test.

Add sharing flag to file open during unsafe image test.
This fixes an issue with the unsafe image test when it's run concurrently.
Without the sharing flag the open can sometimes fails depending on timing
which makes the test flaky.

BUG=594462
Committed: https://crrev.com/699c5f99ffcda70498cf94ba01948261ce5a700d
Cr-Commit-Position: refs/heads/master@{#382128}

[forshaw, 2016-03-14 08:08:45]

forshaw@chromium.org changed reviewers:
+ thakis@chromium.org, wfh@chromium.org

[forshaw, 2016-03-14 08:08:46]

Nico, could you please take a look at this short CL to fix a flaky test. Thanks.

[Will Harris, 2016-03-14 22:45:58]

lgtm

[Nico, 2016-03-18 22:36:45]

lgtm

[Nico, 2016-03-18 22:36:48]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2016-03-18 22:37:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1791383003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1791383003/1

[commit-bot: I haz the power, 2016-03-18 23:17:19]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-18 23:18:23]

Description was changed from

==========
Add sharing flag to file open during unsafe image test.
This fixes an issue with the unsafe image test when it's run concurrently.
Without the sharing flag the open can sometimes fails depending on timing
which makes the test flaky.

BUG=594462
==========

to

==========
Add sharing flag to file open during unsafe image test.
This fixes an issue with the unsafe image test when it's run concurrently.
Without the sharing flag the open can sometimes fails depending on timing
which makes the test flaky.

BUG=594462

Committed: https://crrev.com/699c5f99ffcda70498cf94ba01948261ce5a700d
Cr-Commit-Position: refs/heads/master@{#382128}
==========

[commit-bot: I haz the power, 2016-03-18 23:18:24]

Patchset 1 (id:??) landed as
https://crrev.com/699c5f99ffcda70498cf94ba01948261ce5a700d
Cr-Commit-Position: refs/heads/master@{#382128}