Suppress races reported by ThreadSanitizer v2:
 - race in browser_sync::PasswordChangeProcessor (issue 296862)
 - race in net::URLFetcherCore (issue 296883)

BUG=296883,296862
TBR=oshima@chromium.org

Review URL: https://codereview.chromium.org/23440063

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224705 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224705