Remove stale comment about Chrome Frame.

BUG=316496
NOTRY=true
R=msw@chromium.org

Review URL: https://codereview.chromium.org/138053005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245153 0039d316-1c4b-4281-b951-d872f2087c98