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

ash/mus/sysui_application.cc

Index: ash/mus/sysui_application.cc
diff --git a/ash/mus/sysui_application.cc b/ash/mus/sysui_application.cc
index 91549478aba89a893a37867b2e67028f724a9979..16585a31d4abb7d0c51b6f52f9f233df224449e6 100644
--- a/ash/mus/sysui_application.cc
+++ b/ash/mus/sysui_application.cc
@@ -278,8 +278,7 @@ SysUIApplication::SysUIApplication() {}
 SysUIApplication::~SysUIApplication() {}
 
 void SysUIApplication::Initialize(mojo::Connector* connector,
-                                  const std::string& url,
-                                  const std::string& user_id,
+                                  const mojo::Identity& identity,
                                   uint32_t id) {
   ash_init_.reset(new AshInit());
   ash_init_->Initialize(connector);