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

mash/quick_launch/quick_launch_application.h

Index: mash/quick_launch/quick_launch_application.h
diff --git a/mash/quick_launch/quick_launch_application.h b/mash/quick_launch/quick_launch_application.h
index 8fbd65089d904f3d14895d96df3beb2036288152..130a1ddda3931185cd34ffc4a0863ae87a431749 100644
--- a/mash/quick_launch/quick_launch_application.h
+++ b/mash/quick_launch/quick_launch_application.h
@@ -25,8 +25,7 @@ class QuickLaunchApplication : public mojo::ShellClient {
  private:
   // mojo::ShellClient:
   void Initialize(mojo::Connector* connector,
-                  const std::string& url,
-                  const std::string& user_id,
+                  const mojo::Identity& identity,
                   uint32_t id) override;
   bool AcceptConnection(mojo::Connection* connection) override;