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

mojo/shell/standalone/context.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/shell/standalone/context.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 146 matching lines @@
     app_catalog = std::move(init_params->app_catalog);
   shell_.reset(new Shell(std::move(runner_factory), blocking_pool_.get(),
                          std::move(app_catalog)));
 
   shell::mojom::InterfaceProviderPtr tracing_remote_interfaces;
   shell::mojom::InterfaceProviderPtr tracing_local_interfaces;
   new TracingInterfaceProvider(&tracer_, GetProxy(&tracing_local_interfaces));
 
   scoped_ptr<ConnectParams> params(new ConnectParams);
   params->set_source(CreateShellIdentity());
-  params->set_target(
-      Identity("mojo:tracing", std::string(), mojom::kInheritUserID));
+  params->set_target(Identity("mojo:tracing", mojom::kInheritUserID));
   params->set_remote_interfaces(GetProxy(&tracing_remote_interfaces));
   params->set_local_interfaces(std::move(tracing_local_interfaces));
   shell_->Connect(std::move(params));
 
   if (command_line.HasSwitch(tracing::kTraceStartup)) {
     tracing::TraceCollectorPtr coordinator;
     auto coordinator_request = GetProxy(&coordinator);
     tracing_remote_interfaces->GetInterface(
         tracing::TraceCollector::Name_, coordinator_request.PassMessagePipe());
     tracer_.StartCollectingFromTracingService(std::move(coordinator));
@@ skipping 52 matching lines @@
 }
 
 void Context::Run(const std::string& name) {
   shell_->SetInstanceQuitCallback(base::Bind(&OnInstanceQuit, name));
 
   shell::mojom::InterfaceProviderPtr remote_interfaces;
   shell::mojom::InterfaceProviderPtr local_interfaces;
 
   scoped_ptr<ConnectParams> params(new ConnectParams);
   params->set_source(CreateShellIdentity());
-  params->set_target(Identity(name, std::string(), mojom::kRootUserID));
+  params->set_target(Identity(name, mojom::kRootUserID));
   params->set_remote_interfaces(GetProxy(&remote_interfaces));
   params->set_local_interfaces(std::move(local_interfaces));
   shell_->Connect(std::move(params));
 }
 
 }  // namespace shell
 }  // namespace mojo