Fix uninitialized variable that is making the memory bots unhappy.

BUG=230708
TBR=xhwang@chromium.org

Review URL: https://codereview.chromium.org/116213005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242990 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242990