Mojo: Add more data pipe tests, fix waiting bug.

Oops, I forgot to wake up waiters on read/write.

R=sky@chromium.org

Review URL: https://codereview.chromium.org/118443003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241637 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241637