Fix IWYU violation in password_store_consumer.h

std::vector was used without \#include <vector>. This broke libc++ builds.

TBR=isherman@chromium.org
BUG=318770

Review URL: https://codereview.chromium.org/151483006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249748 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249748