include a test since that needs some work on threading and the testing
interface. I plan on doing that in a separate pass.

TEST=none
BUG=none
Review URL: http://codereview.chromium.org/2712002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@49415 0039d316-1c4b-4281-b951-d872f2087c98