Add means for running some tests only o-o-p, add messaging o-o-p test.

ppapi/ppapi_tests.gypi

 # Copyright (c) 2011 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.
 
 {
   'targets': [
      {
       'target_name': 'ppapi_example',
       'dependencies': [
         'ppapi.gyp:ppapi_cpp'
@@ skipping 54 matching lines @@
         'tests/test_case.cc',
         'tests/test_case.h',
         'tests/testing_instance.cc',
         'tests/testing_instance.h',
 
         # Test cases.
         'tests/all_c_includes.h',
         'tests/all_cpp_includes.h',
         'tests/arch_dependent_sizes_32.h',
         'tests/arch_dependent_sizes_64.h',
+        'tests/pp_thread.h',
         'tests/test_broker.cc',
         'tests/test_broker.h',
         'tests/test_buffer.cc',
         'tests/test_buffer.h',
         'tests/test_c_includes.c',
         'tests/test_char_set.cc',
         'tests/test_char_set.h',
         'tests/test_core.cc',
         'tests/test_core.h',
         'tests/test_cpp_includes.cc',
@@ skipping 255 matching lines @@
           ],
           'sources': [
             'examples/gles2/gles2.cc',
             'examples/gles2/testdata.h',
           ],
         },
       ],
     }]
   ]
 }