Verify server cert using default host CA cert store

      BUG=none
TEST=build with use_openssl=1 and open some https pages

Review URL: http://codereview.chromium.org/3518004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@61355 0039d316-1c4b-4281-b951-d872f2087c98