Mojo: Factor Channel::EndpointInfo out to ChannelEndpoint.

mojo/system/BUILD.gn

 # 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.
 
 config("system_config") {
   defines = [
     # Ensures that dependent projects import the core functions on Windows.
     "MOJO_USE_SYSTEM_IMPL",
   ]
 }
@@ skipping 10 matching lines @@
   defines = [
     "MOJO_SYSTEM_IMPL_IMPLEMENTATION",
     "MOJO_SYSTEM_IMPLEMENTATION",
   ]
 
   all_dependent_configs = [ ":system_config" ]
 
   sources = [
     "channel.cc",
     "channel.h",
+    "channel_endpoint.cc",
+    "channel_endpoint.h",
     "constants.h",
     "core.cc",
     "core.h",
     "data_pipe.cc",
     "data_pipe.h",
     "data_pipe_consumer_dispatcher.cc",
     "data_pipe_consumer_dispatcher.h",
     "data_pipe_producer_dispatcher.cc",
     "data_pipe_producer_dispatcher.h",
     "dispatcher.cc",
@@ skipping 94 matching lines @@
   ]
 
   sources = [
     "message_pipe_perftest.cc",
     "message_pipe_test_utils.h",
     "message_pipe_test_utils.cc",
     "test_utils.cc",
     "test_utils.h",
   ]
 }