Hack for Mac 10.9 hang when the Keychain is modified with Chrome running.

BUG=326011
R=rsleevi@chromium.org
TEST=On 10.9, open Chrome and Keychain Access. Install a certificate in Keychain. Chrome does not hang.

Review URL: https://codereview.chromium.org/106423010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242742 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242742