GMC: Make MediaNotificationBackgroundTest independent of Ash

This CL changes MediaNotificationBackgroundTest to be a subclass of
testing::Test instead of AshTestBase. This makes the test independent
of Ash code and ready to be moved out of Ash.

Bug: 959478
Change-Id: I5ca7648abab8ce392c300f9a3dd69f920f24aeb1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1627652
Reviewed-by: Becca Hughes <beccahughes@chromium.org>
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662840}
1 file changed