Use the Chrome icon rather than a bell icon for notifications

Use the Chrome icon rather than a bell icon for notifications

The generic bell icon is deemed to be confusing, as it creates an
association with alarms rather than generic notifications. Use the
Chrome icon instead.

BUG=523990
Committed: https://crrev.com/1598c3b20079643e0fea748797bf4a6e3c015549
Cr-Commit-Position: refs/heads/master@{#345589}

[Peter Beverloo, 2015-08-25 19:07:45]

peter@chromium.org changed reviewers:
+ miguelg@chromium.org, newt@chromium.org

[Peter Beverloo, 2015-08-25 19:07:46]

+miguelg for notifications, newt for assets

PTAL

[Miguel Garcia, 2015-08-25 19:09:30]

lgtm

[newt (away), 2015-08-25 20:52:27]

lgtm

[Peter Beverloo, 2015-08-26 12:16:56]

The CQ bit was checked by peter@chromium.org

[commit-bot: I haz the power, 2015-08-26 12:17:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1313593003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1313593003/20001

[commit-bot: I haz the power, 2015-08-26 12:21:26]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-26 12:22:12]

Patchset 2 (id:??) landed as
https://crrev.com/1598c3b20079643e0fea748797bf4a6e3c015549
Cr-Commit-Position: refs/heads/master@{#345589}