net: don't include subdomains for play.google.com HSTS.

BUG=327834
R=palmer@chromium.org

Review URL: https://codereview.chromium.org/125313002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243153 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243153