Include mojo_main_{chromium,standalone}.cc instead of using a target

mojo/mojo_services.gypi

 {
   'targets': [
     {
       'target_name': 'mojo_echo_bindings',
       'type': 'static_library',
       'sources': [
         'services/dbus_echo/echo.mojom',
       ],
       'includes': [ 'public/tools/bindings/mojom_bindings_generator.gypi' ],
       'export_dependent_settings': [
@@ skipping 313 matching lines @@
         {
           'target_name': 'mojo_view_manager',
           'type': '<(component)',
           'dependencies': [
             '../base/base.gyp:base',
             '../skia/skia.gyp:skia',
             '../ui/aura/aura.gyp:aura',
             '../ui/base/ui_base.gyp:ui_base',
             '../ui/gfx/gfx.gyp:gfx',
             '../ui/gfx/gfx.gyp:gfx_geometry',
+            'mojo_application',
             'mojo_aura_support',
             'mojo_common_lib',
             'mojo_environment_chromium',
             'mojo_geometry_bindings',
             'mojo_geometry_lib',
             'mojo_gles2',
             'mojo_input_events_bindings',
             'mojo_input_events_lib',
             'mojo_launcher_bindings',
-            'mojo_main_chromium',
             'mojo_native_viewport_bindings',
             'mojo_system_impl',
             'mojo_view_manager_bindings',
             'mojo_view_manager_common',
           ],
           'sources': [
+            'public/cpp/application/lib/mojo_main_chromium.cc',
             'services/view_manager/ids.h',
             'services/view_manager/main.cc',
             'services/view_manager/node.cc',
             'services/view_manager/node.h',
             'services/view_manager/node_delegate.h',
             'services/view_manager/root_node_manager.cc',
             'services/view_manager/root_node_manager.h',
             'services/view_manager/root_view_manager.cc',
             'services/view_manager/root_view_manager.h',
             'services/view_manager/root_view_manager_delegate.h',
@@ skipping 79 matching lines @@
             'mojo_system_impl',
           ],
           'sources': [
             'services/dbus_echo/dbus_echo_service.cc',
           ],
         },
       ],
     }],
   ],
 }