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

components/font_service/font_service_app.cc

Index: components/font_service/font_service_app.cc
diff --git a/components/font_service/font_service_app.cc b/components/font_service/font_service_app.cc
index d0c0c1c5d167c9956f3d27c2ca69b6ddeba62deb..6e73b9996236866fa043120d74c8a69638f49cd5 100644
--- a/components/font_service/font_service_app.cc
+++ b/components/font_service/font_service_app.cc
@@ -59,9 +59,9 @@ FontServiceApp::FontServiceApp() {}
 FontServiceApp::~FontServiceApp() {}
 
 void FontServiceApp::Initialize(mojo::Connector* connector,
-                                const std::string& url,
-                                const std::string& user_id, uint32_t id) {
-  tracing_.Initialize(connector, url);
+                                const mojo::Identity& identity,
+                                uint32_t id) {
+  tracing_.Initialize(connector, identity.name());
 }
 
 bool FontServiceApp::AcceptConnection(mojo::Connection* connection) {