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

mojo/shell/tests/shell/target.cc

Index: mojo/shell/tests/shell/target.cc
diff --git a/mojo/shell/tests/shell/target.cc b/mojo/shell/tests/shell/target.cc
index 3f75dc9be609aa67f9e9773c1cf9e06f6c456e44..e05a9dc33181f243a4862a39ba0cba63f84d7cb1 100644
--- a/mojo/shell/tests/shell/target.cc
+++ b/mojo/shell/tests/shell/target.cc
@@ -23,8 +23,8 @@ class Target : public mojo::ShellClient {
 
  private:
   // mojo::ShellClient:
-  void Initialize(mojo::Connector* connector, const std::string& name,
-                  const std::string& user_id, uint32_t id) override {
+  void Initialize(mojo::Connector* connector, const mojo::Identity& identity,
+                  uint32_t id) override {
     CreateInstanceTestPtr service;
     connector->ConnectToInterface("mojo:shell_unittest", &service);
     service->SetTargetID(id);