[Files.app] Remove the unused constants in SuggestAppsDialog

BUG=none
TEST=manual
R=hirono@chromium.org

Review URL: https://codereview.chromium.org/24220005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226196 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226196