[Extensions UI] Check for a browser not being found

[Extensions UI] Check for a browser not being found

chrome::FindBrowserWithWebContents() can return null in some cases.
Guard against it in showing the warning bubble.

BUG=631362
Committed: https://crrev.com/8996565733bc75e7a029e8b8d4612e2b013e63d2
Cr-Commit-Position: refs/heads/master@{#408403}

[Devlin, 2016-07-27 22:51:01]

The CQ bit was checked by rdevlin.cronin@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-07-27 22:51:41]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-27 23:06:11]

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

[commit-bot: I haz the power, 2016-07-27 23:06:13]

Dry run: Try jobs failed on following builders:
  android_arm64_dbg_recipe on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_arm6...)

[Devlin, 2016-07-28 00:15:53]

rdevlin.cronin@chromium.org changed reviewers:
+ benwells@chromium.org

[Devlin, 2016-07-28 00:15:54]

Hey Ben, Finnur's out for the summer; mind taking a quick look?

[benwells, 2016-07-28 07:52:00]

lgtm

[Devlin, 2016-07-28 15:00:49]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2016-07-28 15:01:15]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-28 15:44:52]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-07-28 15:46:12]

Description was changed from

==========
[Extensions UI] Check for a browser not being found

chrome::FindBrowserWithWebContents() can return null in some cases.
Guard against it in showing the warning bubble.

BUG=631362
==========

to

==========
[Extensions UI] Check for a browser not being found

chrome::FindBrowserWithWebContents() can return null in some cases.
Guard against it in showing the warning bubble.

BUG=631362

Committed: https://crrev.com/8996565733bc75e7a029e8b8d4612e2b013e63d2
Cr-Commit-Position: refs/heads/master@{#408403}
==========

[commit-bot: I haz the power, 2016-07-28 15:46:13]

Patchset 1 (id:??) landed as
https://crrev.com/8996565733bc75e7a029e8b8d4612e2b013e63d2
Cr-Commit-Position: refs/heads/master@{#408403}