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

components/mus/mus_app.h

 // Copyright 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.
 
 #ifndef COMPONENTS_MUS_MUS_APP_H_
 #define COMPONENTS_MUS_MUS_APP_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 45 matching lines @@
   ~MandolineUIServicesApp() override;
 
  private:
   // Holds InterfaceRequests received before the first WindowTreeHost Display
   // has been established.
   struct PendingRequest;
 
   void InitializeResources(mojo::Connector* connector);
 
   // mojo::ShellClient:
-  void Initialize(mojo::Connector* connector, const std::string& url,
-                  const std::string& user_id, uint32_t id) override;
+  void Initialize(mojo::Connector* connector, const mojo::Identity& identity,
+                  uint32_t id) override;
   bool AcceptConnection(mojo::Connection* connection) override;
 
   // ConnectionManagerDelegate:
   void OnFirstDisplayReady() override;
   void OnNoMoreDisplays() override;
   scoped_ptr<ws::WindowTreeBinding> CreateWindowTreeBindingForEmbedAtWindow(
       ws::ConnectionManager* connection_manager,
       ws::WindowTree* tree,
       mojom::WindowTreeRequest tree_request,
       mojom::WindowTreeClientPtr client) override;
@@ skipping 34 matching lines @@
 
   // Surfaces
   scoped_refptr<SurfacesState> surfaces_state_;
 
   DISALLOW_COPY_AND_ASSIGN(MandolineUIServicesApp);
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_MUS_APP_H_