[mojo-edk] Add support for transferring mach ports.

mojo/edk/test/multiprocess_test_helper.h

Index: mojo/edk/test/multiprocess_test_helper.h
diff --git a/mojo/edk/test/multiprocess_test_helper.h b/mojo/edk/test/multiprocess_test_helper.h
index 7ee60247af612361e066da10097b180fab105182..b3bed6b5bd4c0e7f0b151b69b5bb7f2cb03b05f9 100644
--- a/mojo/edk/test/multiprocess_test_helper.h
+++ b/mojo/edk/test/multiprocess_test_helper.h
@@ -55,6 +55,8 @@ class MultiprocessTestHelper {
   // |EXPECT_TRUE(WaitForChildTestShutdown());|.
   bool WaitForChildTestShutdown();
 
+  const base::Process& test_child() const { return test_child_; }
+
   // Used by macros in mojo/edk/test/mojo_test_base.h to support multiprocess
   // test client initialization.
   static void ChildSetup();