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

mojo/mojo_base.gyp

 # Copyright 2014 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.
 
 # Essential components (and their tests) that are needed to build
 # Chrome should be here.  Other components that are useful only in
 # Mojo land like mojo_shell should be in mojo.gyp.
 {
   'includes': [
     'mojo_variables.gypi',
@@ skipping 182 matching lines @@
     },
     {
       # GN version: //mojo/shell/public/cpp
       'target_name': 'mojo_application_base',
       'type': 'static_library',
       'sources': [
         'shell/public/cpp/application_runner.h',
         'shell/public/cpp/connect.h',
         'shell/public/cpp/connection.h',
         'shell/public/cpp/connector.h',
+        'shell/public/cpp/identity.h',
         'shell/public/cpp/initialize_base_and_icu.cc',
         'shell/public/cpp/initialize_base_and_icu.h',
         'shell/public/cpp/interface_binder.h',
         'shell/public/cpp/interface_factory.h',
         'shell/public/cpp/interface_factory_impl.h',
         'shell/public/cpp/interface_registry.h',
         'shell/public/cpp/lib/application_runner.cc',
         'shell/public/cpp/lib/connection_impl.cc',
         'shell/public/cpp/lib/connection_impl.h',
         'shell/public/cpp/lib/connector_impl.cc',
         'shell/public/cpp/lib/connector_impl.h',
+        'shell/public/cpp/lib/identity.cc',
         'shell/public/cpp/lib/interface_factory_binder.h',
         'shell/public/cpp/lib/interface_registry.cc',
         'shell/public/cpp/lib/message_loop_ref.cc',
         'shell/public/cpp/lib/names.cc',
         'shell/public/cpp/lib/shell_client.cc',
         'shell/public/cpp/lib/shell_connection.cc',
         'shell/public/cpp/message_loop_ref.h',
         'shell/public/cpp/names.h',
         'shell/public/cpp/shell.h',
         'shell/public/cpp/shell_client.h',
@@ skipping 161 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'mojo_common_unittests.isolate',
           ],
         },
       ],
     }],
   ]
 }