Do something more interesting than printf when an event is received by sample_app.

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

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=239910

Review URL: https://codereview.chromium.org/108273008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240040 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240040