Fix memory error in previous CL.

BUG=100315
BUG=99016
TEST=Memory bots go green

Review URL: http://codereview.chromium.org/8302001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@105577 0039d316-1c4b-4281-b951-d872f2087c98
  TabContentsWrapper* ReleaseOwnership() {
    return target_contents_owner_.release();
  }

  TabContentsWrapper* ReleaseOwnership() {
    return target_contents_owner_.release();
  }
