Reland "libprocessgroup: return false on failure"

This reverts commit c109b13b5a72f9dd357864f7fe5748c81b4f2310.

Reason for revert: uploading with a CL fixing the broken test

Change-Id: I97a0a49ded8bc17c2d70c82f8e48fce09e49b2bd
1 file changed