As promised, add a unit test that makes sure the in app payments app gets installed and is enabled.

BUG=313797
R=asargent@chromium.org

Review URL: https://codereview.chromium.org/65303003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235206 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235206