Mojo: Add a more end-to-end-ish test of handle passing (across a "remote" message pipe).

R=darin@chromium.org

Review URL: https://codereview.chromium.org/180163018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255067 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255067