Require an explicit ServiceName annotation for interfaces in Python.

mojo/public/python/mojo_application/application_impl.py

 # Copyright 2015 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.
 
 """Python implementation of the Application interface."""
 
+import logging
+
 import application_mojom
 import service_provider_mojom
 import shell_mojom
 from mojo_application.service_provider_impl import ServiceProviderImpl
 
 import mojo_system
 
 class ApplicationImpl(application_mojom.Application):
   def __init__(self, delegate, app_request_handle):
     self.shell = None
@@ skipping 22 matching lines @@
       def removeServiceProvider():
         self._providers.remove(service_provider)
       service_provider.manager.AddOnErrorCallback(removeServiceProvider)
 
   def ConnectToService(self, application_url, service_class):
     """
     Helper method to connect to a service. |application_url| is the URL of the
     application to be connected to, and |service_class| is the class of the
     service to be connected to. Returns a proxy to the service.
     """
+    if not service_class.service_name:

[qsr, 2015/12/10 15:13:53]

I think service_name should be in the manager class, not on the class itself. We
are trying not to restrict the number of collision that can happen as much as
possible.

+      logging.error("No ServiceName specified for %s." % service_class.__name__)
+      return
     application_proxy, request = (
         service_provider_mojom.ServiceProvider.manager.NewRequest())
     self.shell.ConnectToApplication(application_url, request, None)
 
     service_proxy, request = service_class.manager.NewRequest()
-    application_proxy.ConnectToService(service_class.manager.name,
+    application_proxy.ConnectToService(service_class.service_name,
                                        request.PassMessagePipe())
 
     return service_proxy