Fix MenuPreTargetHandler Crash

Fix MenuPreTargetHandler Crash

Apparently StatusIconWin runs a menu without providing a widget. MenuPreTargetHandler had assumed there would always be a widget to listen to. This change updates that to not attempt to listen when there is no widget.

TEST=MenuControllerTest.RunWithoutWidgetDoesntCrash
BUG=633897
Committed: https://crrev.com/e1038c1c30e9ec9e5cbb08b3f34eb6635c230696
Cr-Commit-Position: refs/heads/master@{#409648}

[jonross, 2016-08-03 19:50:25]

jonross@chromium.org changed reviewers:
+ sky@chromium.org

[jonross, 2016-08-03 19:50:25]

Sky@ could you take a look at this change? It addresses a crash that was found
in Windows.

[sky, 2016-08-03 21:30:08]

LGTM

[jonross, 2016-08-03 21:40:51]

The CQ bit was checked by jonross@chromium.org

[commit-bot: I haz the power, 2016-08-03 21:41:24]

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, 2016-08-03 22:49:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-03 22:51:16]

Description was changed from

==========
Fix MenuPreTargetHandler Crash

Apparently StatusIconWin runs a menu without providing a widget.
MenuPreTargetHandler had assumed there would always be a widget to listen to.
This change updates that to not attempt to listen when there is no widget.

TEST=MenuControllerTest.RunWithoutWidgetDoesntCrash
BUG=633897
==========

to

==========
Fix MenuPreTargetHandler Crash

Apparently StatusIconWin runs a menu without providing a widget.
MenuPreTargetHandler had assumed there would always be a widget to listen to.
This change updates that to not attempt to listen when there is no widget.

TEST=MenuControllerTest.RunWithoutWidgetDoesntCrash
BUG=633897

Committed: https://crrev.com/e1038c1c30e9ec9e5cbb08b3f34eb6635c230696
Cr-Commit-Position: refs/heads/master@{#409648}
==========

[commit-bot: I haz the power, 2016-08-03 22:51:17]

Patchset 1 (id:??) landed as
https://crrev.com/e1038c1c30e9ec9e5cbb08b3f34eb6635c230696
Cr-Commit-Position: refs/heads/master@{#409648}