Change userid from a uint32_t to a string guid

mojo/shell/tests/connect/connect_test_app.cc

Index: mojo/shell/tests/connect/connect_test_app.cc
diff --git a/mojo/shell/tests/connect/connect_test_app.cc b/mojo/shell/tests/connect/connect_test_app.cc
index 875b7ff24fbad9e2b011c9fd0c0aa8b8917ce5ed..3951a6f1c127e535449415d969ae08a911bdcc37 100644
--- a/mojo/shell/tests/connect/connect_test_app.cc
+++ b/mojo/shell/tests/connect/connect_test_app.cc
@@ -34,7 +34,7 @@ class ConnectTestApp : public ShellClient,
  private:
   // mojo::ShellClient:
   void Initialize(Connector* connector, const std::string& name,
-                  uint32_t id, uint32_t user_id) override {
+                  const std::string& user_id, uint32_t id) override {
     connector_ = connector;
     name_ = name;
     id_ = id;
@@ -141,7 +141,7 @@ class ConnectTestApp : public ShellClient,
   Connector* connector_ = nullptr;
   std::string name_;
   uint32_t id_ = mojom::Connector::kInvalidApplicationID;
-  uint32_t userid_ = mojom::Connector::kUserRoot;
+  std::string userid_ = mojom::kRootUserID;
   BindingSet<test::mojom::ConnectTestService> bindings_;
   BindingSet<test::mojom::StandaloneApp> standalone_bindings_;
   BindingSet<test::mojom::BlockedInterface> blocked_bindings_;