Use PASS() everywhere in ppapi/tests.

ppapi/tests/test_transport.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ppapi/tests/test_transport.h"
 
 #include <string.h>
 
 #include <string>
 
@@ skipping 14 matching lines @@
   return transport_interface_ && InitTestingInterface();
 }
 
 void TestTransport::RunTest() {
   RUN_TEST(FirstTransport);
   // TODO(juberti): more Transport tests here...
 }
 
 std::string TestTransport::TestFirstTransport() {
   // TODO(juberti): actual test
-  return "";
+  PASS();
 }