desktop notification test setup: valid ShellDelegate, create ActiveDesktopMonitor

desktop notification test setup: valid ShellDelegate, create ActiveDesktopMonitor

Two fixes for DesktopNotificationTest.* on win_aura:
- was creating a ShellInstance with a NULL delegate which Shell DCHECKs on: pull in ash::test::TestShellDelegate
- wasn't creating an ActiveDesktopMonitor, so instantiate one for test purposes.

Also, change a couple USE_AURAs that look like they should be USE_ASHs.

R=grt@chromium.org, stevenjb@chromium.org
TEST=browser_tests on win_aura, DesktopNotificationTest.*


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=169181

[stevenjb, 2012-11-21 21:52:42]

lgtm

[commit-bot: I haz the power, 2012-11-21 23:04:31]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/scottmg@chromium.org/11416145/1

[commit-bot: I haz the power, 2012-11-22 01:03:38]

Change committed as 169181

[grt (UTC plus 2), 2012-11-22 02:55:38]

lgtm+1.  thanks.