Add a instance groups to Connect(), and introduce an Identity struct.

media/mojo/services/mojo_media_application.h

Index: media/mojo/services/mojo_media_application.h
diff --git a/media/mojo/services/mojo_media_application.h b/media/mojo/services/mojo_media_application.h
index 9844ab135421d1fcbcf0789f1c4f0ef6122fd0b2..c004e83cfc7db63328909c9c7667aa96f23cfa83 100644
--- a/media/mojo/services/mojo_media_application.h
+++ b/media/mojo/services/mojo_media_application.h
@@ -28,8 +28,7 @@ class MojoMediaApplication
  private:
   // mojo::ShellClient implementation.
   void Initialize(mojo::Connector* connector,
-                  const std::string& url,
-                  const std::string& user_id,
+                  const mojo::Identity& identity,
                   uint32_t id) final;
   bool AcceptConnection(mojo::Connection* connection) final;