cros: Use AlertDialog for remora device requisition.

BUG=313854

Review URL: https://codereview.chromium.org/61523002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233547 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233547