Added test to ensure app banner settings are per-origin.

Added test to ensure app banner settings are per-origin.

The banner engagement persisted data should be per-origin. This test
ensures that is the case.

BUG=468148
Committed: https://crrev.com/500bbc41a2711ee5ba4d22ae4b3d16fa5867d30a
Cr-Commit-Position: refs/heads/master@{#321409}

[benwells, 2015-03-19 07:54:27]

benwells@chromium.org changed reviewers:
+ dfalcantara@chromium.org

[gone, 2015-03-19 16:46:56]

lgtm

[benwells, 2015-03-19 19:23:20]

The CQ bit was checked by benwells@chromium.org

[commit-bot: I haz the power, 2015-03-19 19:24:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1019763002/1

[commit-bot: I haz the power, 2015-03-19 19:37:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-19 19:38:28]

Patchset 1 (id:??) landed as
https://crrev.com/500bbc41a2711ee5ba4d22ae4b3d16fa5867d30a
Cr-Commit-Position: refs/heads/master@{#321409}