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

components/filesystem/file_system_app.cc

Index: components/filesystem/file_system_app.cc
diff --git a/components/filesystem/file_system_app.cc b/components/filesystem/file_system_app.cc
index e4620ba8126d0c4ad9260c38977aeca1a722d532..011f74d78f425911cc4aed822af217ffca1b3291 100644
--- a/components/filesystem/file_system_app.cc
+++ b/components/filesystem/file_system_app.cc
@@ -38,10 +38,9 @@ FileSystemApp::FileSystemApp() : lock_table_(new LockTable) {}
 FileSystemApp::~FileSystemApp() {}
 
 void FileSystemApp::Initialize(mojo::Connector* connector,
-                               const std::string& url,
-                               const std::string& user_id,
+                               const mojo::Identity& identity,
                                uint32_t id) {
-  tracing_.Initialize(connector, url);
+  tracing_.Initialize(connector, identity.name());
 }
 
 bool FileSystemApp::AcceptConnection(mojo::Connection* connection) {