Modify behavior of --bypass-app-banner-engagement-checks flag.

Modify behavior of --bypass-app-banner-engagement-checks flag.

This flag now does not bypass the checks for whether the app has been
added to the homescreen or not.

BUG=467374
Committed: https://crrev.com/7f20516eaeaa5fcf2e0a685a3b048c1fdb9a856f
Cr-Commit-Position: refs/heads/master@{#320968}

[benwells, 2015-03-17 06:33:30]

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

[gone, 2015-03-17 16:55:16]

lgtm

[benwells, 2015-03-17 20:48:32]

The CQ bit was checked by benwells@chromium.org

[commit-bot: I haz the power, 2015-03-17 20:49:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1011963003/1

[commit-bot: I haz the power, 2015-03-17 20:54:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-17 20:55:45]

Patchset 1 (id:??) landed as
https://crrev.com/7f20516eaeaa5fcf2e0a685a3b048c1fdb9a856f
Cr-Commit-Position: refs/heads/master@{#320968}