mojom: Add associative arrays to the mojom language.

mojo/mojo_services.gypi

 # Copyright (c) 2014 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': [
     {
       # GN version: //mojo/services/clipboard/
       'target_name': 'mojo_clipboard',
       'type': 'loadable_module',
@@ skipping 13 matching lines @@
       ],
     },
     {
       # GN version: //mojo/services/public/interfaces/clipboard
       'target_name': 'mojo_clipboard_bindings',
       'type': 'static_library',
       'sources': [
         'services/public/interfaces/clipboard/clipboard.mojom',
       ],
       'includes': [ 'public/tools/bindings/mojom_bindings_generator.gypi' ],
+      'variables': {
+        # TODO(erg): Expand this as we add map support to other bindings.
+        'mojom_additional_args': ['-g=c++'],
+      },
       'dependencies': [
         'mojo_base.gyp:mojo_cpp_bindings',
       ],
       'export_dependent_settings': [
         'mojo_base.gyp:mojo_cpp_bindings',
       ],
     },
     {
       # GN version: //mojo/services/clipboard:mojo_clipboard_unittests
       'target_name': 'mojo_clipboard_unittests',
@@ skipping 935 matching lines @@
               'dependencies': [
                 '../ui/gfx/x/gfx_x11.gyp:gfx_x11',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }