GitLab

Add a separate histogram label for GWS based prerendering.
R=cbentzel@chromium.org, dominich@chromium.org
Review URL: http://codereview.chromium.org/7605020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@96227 0039d316-1c4b-4281-b951-d872f2087c98