GitLab

Make PowerButtonController ignore power button events when
the screen is turned off -- if the user hits the power
button to turn the screen back on, we don't want to lock or
shutdown if they hold it a bit too long.

BUG=128451
TEST=added, also did manual testing


Review URL: https://chromiumcodereview.appspot.com/10382211

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137679 0039d316-1c4b-4281-b951-d872f2087c98