Check if BubbleReference weak pointer is valid before using it in the chooser

Check if BubbleReference weak pointer is valid before using it in the chooser

Since BubbleReference is a base::WeakPtr<BubbleController>, before
using it, needs to check if it is valid. This CL added code to do it.

BUG=642748
Committed: https://crrev.com/76f6b1648624d9fe6ce48b7d5996e3c2d41ec710
Cr-Commit-Position: refs/heads/master@{#416698}

[juncai, 2016-09-02 23:22:39]

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

[commit-bot: I haz the power, 2016-09-02 23:23:29]

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

[juncai, 2016-09-02 23:25:53]

juncai@chromium.org changed reviewers:
+ msw@chromium.org, rsesek@chromium.org

[juncai, 2016-09-02 23:25:54]

rsesek@chromium.org: Please review changes in 
//chrome/browser/ui/cocoa

msw@chromium.org: Please review changes in 
//chrome/browser/ui/views/

[commit-bot: I haz the power, 2016-09-03 00:11:13]

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

[commit-bot: I haz the power, 2016-09-03 00:11:13]

Dry run: This issue passed the CQ dry run.

[Robert Sesek, 2016-09-06 15:40:25]

lgtm

[msw, 2016-09-06 19:15:25]

lgtm

[juncai, 2016-09-06 19:25:41]

The CQ bit was checked by juncai@chromium.org

[commit-bot: I haz the power, 2016-09-06 19:26:25]

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, 2016-09-06 20:24:12]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-09-06 20:26:36]

Description was changed from

==========
Check if BubbleReference weak pointer is valid before using it in the chooser

Since BubbleReference is a base::WeakPtr<BubbleController>, before
using it, needs to check if it is valid. This CL added code to do it.

BUG=642748
==========

to

==========
Check if BubbleReference weak pointer is valid before using it in the chooser

Since BubbleReference is a base::WeakPtr<BubbleController>, before
using it, needs to check if it is valid. This CL added code to do it.

BUG=642748

Committed: https://crrev.com/76f6b1648624d9fe6ce48b7d5996e3c2d41ec710
Cr-Commit-Position: refs/heads/master@{#416698}
==========

[commit-bot: I haz the power, 2016-09-06 20:26:37]

Patchset 2 (id:??) landed as
https://crrev.com/76f6b1648624d9fe6ce48b7d5996e3c2d41ec710
Cr-Commit-Position: refs/heads/master@{#416698}