Factor out a perf test result printer method.

This is to allow cc_perftests to share this code without depending on chrome/.

BUG=

Review URL: https://chromiumcodereview.appspot.com/23509002

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@220803 4ff67af0-8c30-449e-8e8b-ad334ec8d88c