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

components/font_service/font_service_app.h

Index: components/font_service/font_service_app.h
diff --git a/components/font_service/font_service_app.h b/components/font_service/font_service_app.h
index 52b1f030122750e25d4d46803a10873318b7ef0e..957f231f7b2518968c2307c6b33aa95a58fcabe8 100644
--- a/components/font_service/font_service_app.h
+++ b/components/font_service/font_service_app.h
@@ -27,8 +27,8 @@ class FontServiceApp : public mojo::ShellClient,
 
  private:
   // 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;
 
   // mojo::InterfaceFactory<FontService>: