Implement a trivial Mojo EchoService that can be connected to over DBus

mojo/mojo_services.gypi

 {
   'targets': [
     {
+      'target_name': 'mojo_echo_bindings',
+      'type': 'static_library',
+      'sources': [
+        'services/dbus_echo/echo.mojom',
+      ],
+      'variables': {
+        'mojom_base_output_dir': 'mojo',
+      },
+      'includes': [ 'public/tools/bindings/mojom_bindings_generator.gypi' ],
+      'export_dependent_settings': [
+        'mojo_bindings',
+      ],
+      'dependencies': [
+        'mojo_bindings',
+      ],
+    },
+    {
       'target_name': 'mojo_gles2_bindings',
       'type': 'static_library',
       'sources': [
         'services/gles2/command_buffer.mojom',
         'services/gles2/command_buffer_type_conversions.cc',
         'services/gles2/command_buffer_type_conversions.h',
         'services/gles2/mojo_buffer_backing.cc',
         'services/gles2/mojo_buffer_backing.h',
       ],
       'variables': {
@@ skipping 201 matching lines @@
         },
         {
           'target_name': 'package_mojo_view_manager',
           'variables': {
             'app_name': 'mojo_view_manager',
           },
           'includes': [ 'build/package_app.gypi' ],
         },
       ],
     }],
+    ['OS=="linux"', {
+      'targets': [
+        {
+          'target_name': 'mojo_dbus_echo_service',
+          'type': 'executable',
+          'dependencies': [
+            '../base/base.gyp:base',
+            '../build/linux/system.gyp:dbus',
+            '../dbus/dbus.gyp:dbus',
+            'mojo_external_service_bindings',
+            'mojo_common_lib',
+            'mojo_environment_chromium',
+            'mojo_echo_bindings',
+            'mojo_shell_client',
+            'mojo_system_impl',
+          ],
+          'sources': [
+            'services/dbus_echo/dbus_echo_service.cc',
+          ],
+        },
+      ],
+    }],
   ],
 }