Reenable UILayoutTest.MediaUILayoutTest on Linux
Reenable UILayoutTest.MediaUILayoutTest on Linux

MediaUILayoutTest passes on linux locally, so this reenables the test
and marks it as flaky for linux.

BUG=56364
TEST=ui_tests

Review URL: http://codereview.chromium.org/5533001

git-svn-id: http://src.chromium.org/svn/trunk/src@68801 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 6cd49b811eda6b48aba8c16dfb85cbb6d60392d1
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser