In order to have something for implementors to look at, let's add
this extension here. We can always replace it with a newer version
once we have everything specced.
BUG=chromium:366935
TEST=no test
Review URL: https://codereview.chromium.org/478453003
Cr-Commit-Position: refs/heads/master@{#289893}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289893 0039d316-1c4b-4281-b951-d872f2087c98