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

components/leveldb/leveldb_app.cc

Index: components/leveldb/leveldb_app.cc
diff --git a/components/leveldb/leveldb_app.cc b/components/leveldb/leveldb_app.cc
index 3dfd509d73fcac0c2330733f307447e724dd0cc3..4ac0ca0d83253e52dca0eb910796d05d275a2248 100644
--- a/components/leveldb/leveldb_app.cc
+++ b/components/leveldb/leveldb_app.cc
@@ -14,10 +14,9 @@ LevelDBApp::LevelDBApp() {}
 LevelDBApp::~LevelDBApp() {}
 
 void LevelDBApp::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());
   service_.reset(new LevelDBServiceImpl);
 }