Fix crash when pressing stylus tools accelerator with null PaletteTray.

Fix crash when pressing stylus tools accelerator with null PaletteTray.

BUG=717422
Review-Url: https://codereview.chromium.org/2858583002
Cr-Commit-Position: refs/heads/master@{#468651}
Committed: https://chromium.googlesource.com/chromium/src/+/be86e8abc1a85b3cdb7b575ed1f5d6a6bbbfd460

[Evan Stade, 2017-05-02 15:18:42]

estade@chromium.org changed reviewers:
+ jamescook@chromium.org, jdufault@chromium.org

[Evan Stade, 2017-05-02 15:18:43]

palette_tray_ is created conditionally so I guess it can be null in some
scenario (clusterfuzz only?). The main change here is checking for nullness of
palette_tray(). I moved the checks to CanHandleShowStylusTools because it seems
more appropriate there and prevents logging an accelerator use.

[Evan Stade, 2017-05-02 15:18:46]

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

[commit-bot: I haz the power, 2017-05-02 15:19:09]

Dry run: CQ is trying da patch.

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

[James Cook, 2017-05-02 15:37:01]

LGTM. I just filed a bug for the underlying issue, crbug.com/717559 - but I
think this is the right thing to do for now.

[Evan Stade, 2017-05-02 15:49:57]

The CQ bit was unchecked by estade@chromium.org

[Evan Stade, 2017-05-02 15:50:00]

The CQ bit was checked by estade@chromium.org

[commit-bot: I haz the power, 2017-05-02 15:50:11]

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, 2017-05-02 15:58:40]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1493740200083230,
"parent_rev": "2d76b52e99c335398b390d2009188d7a4037bd97", "commit_rev":
"be86e8abc1a85b3cdb7b575ed1f5d6a6bbbfd460"}

[commit-bot: I haz the power, 2017-05-02 15:58:49]

Description was changed from

==========
Fix crash when pressing stylus tools accelerator with null PaletteTray.

BUG=717422
==========

to

==========
Fix crash when pressing stylus tools accelerator with null PaletteTray.

BUG=717422

Review-Url: https://codereview.chromium.org/2858583002
Cr-Commit-Position: refs/heads/master@{#468651}
Committed:
https://chromium.googlesource.com/chromium/src/+/be86e8abc1a85b3cdb7b575ed1f5...
==========

[commit-bot: I haz the power, 2017-05-02 15:58:56]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/be86e8abc1a85b3cdb7b575ed1f5...