Move functionality out of AppContextMenu and into AppListControllerDelegate.

BUG=310376

Review URL: https://codereview.chromium.org/36273002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230383 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230383