Wire events through to sample_app

R=abarth@chromium.org
http://crbug.com/324639

Review URL: https://codereview.chromium.org/100823010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239233 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239233