Mojo: Add logging macros (and supporting code) for use in mojo/public/cpp.

mojo/mojo.gyp

 # Copyright 2013 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.
 
 {
   'target_defaults': {
     'conditions': [
       ['mojo_shell_debug_url != ""', {
         'defines': [
           'MOJO_SHELL_DEBUG=1',
@@ skipping 377 matching lines @@
     {
       # GN version: //mojo/environment:chromium
       'target_name': 'mojo_environment_chromium',
       'type': 'static_library',
       'dependencies': [
         'mojo_common_lib',
         'mojo_environment_chromium_impl',
       ],
       'sources': [
         'environment/environment.cc',
+        # TODO(vtl): This is kind of ugly. (See TODO in logging.h.)
+        "public/cpp/environment/logging.h",
+        "public/cpp/environment/lib/logging.h",
       ],
       'include_dirs': [
         '..',
       ],
       'export_dependent_settings': [
         'mojo_environment_chromium_impl',
       ],
     },
     {
       # GN version: //mojo/environment:chromium_impl
@@ skipping 533 matching lines @@
             'views/native_widget_view_manager.cc',
             'views/native_widget_view_manager.h',
             'views/views_init.cc',
             'views/views_init.h',
           ],
         },
       ],
     }],
   ],
 }