app_list::StartPageService: Document and check nulls.

app_list::StartPageService: Document and check nulls.

This adds null checks for the result of StartPageService::Get in a few
places where it was missing.

Committed: https://crrev.com/6a94f6890f6130e11c62aa1642d307d1f2c69e05
Cr-Commit-Position: refs/heads/master@{#318985}

[Matt Giuca, 2015-03-03 03:58:24]

mgiuca@chromium.org changed reviewers:
+ calamity@chromium.org, xiyuan@chromium.org

[xiyuan, 2015-03-03 04:45:16]

lgtm

[calamity, 2015-03-03 07:27:31]

lgtm.

[Matt Giuca, 2015-03-03 22:54:11]

The CQ bit was checked by mgiuca@chromium.org

[commit-bot: I haz the power, 2015-03-03 22:55:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/970863003/1

[commit-bot: I haz the power, 2015-03-04 00:56:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-04 00:56:48]

Patchset 1 (id:??) landed as
https://crrev.com/6a94f6890f6130e11c62aa1642d307d1f2c69e05
Cr-Commit-Position: refs/heads/master@{#318985}