Add missing 'return' keyword.

Discovered with experimental Clang plugin that flags temporary objects
that are immediately destroyed.

patch from issue 1359063003 at patchset 1 (http://crrev.com/1359063003#ps1)

A=mdempsky@chromium.org
R=mdempsky@chromium.org

Review URL: https://codereview.chromium.org/1359103002 .
1 file changed