Remove some InterfacePtr<> methods which directly deal with message pipe handles.

mojo/public/cpp/application/lib/application_test_base.cc

Index: mojo/public/cpp/application/lib/application_test_base.cc
diff --git a/mojo/public/cpp/application/lib/application_test_base.cc b/mojo/public/cpp/application/lib/application_test_base.cc
index af6e13a29110eccb58b688b4efa0e799e85612d5..c4ec87a275b8f8a41edc06653bbfd223089a1b9c 100644
--- a/mojo/public/cpp/application/lib/application_test_base.cc
+++ b/mojo/public/cpp/application/lib/application_test_base.cc
@@ -115,7 +115,7 @@ MojoResult RunAllTests(MojoHandle application_request_handle) {
 
   // Shut down our message pipes before exiting.
   (void)g_application_request.PassMessagePipe();
-  (void)g_shell.PassMessagePipe();
+  (void)g_shell.PassInterface();
 
   return (result == 0) ? MOJO_RESULT_OK : MOJO_RESULT_UNKNOWN;
 }