Add a content API to create a message channel.

content/content_browser.gypi

 # Copyright (c) 2012 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base_static',
     '../crypto/crypto.gyp:crypto',
     '../device/battery/battery.gyp:device_battery',
     '../device/battery/battery.gyp:device_battery_mojo_bindings',
@@ skipping 127 matching lines @@
       'public/browser/javascript_dialog_manager.h',
       'public/browser/load_from_memory_cache_details.cc',
       'public/browser/load_from_memory_cache_details.h',
       'public/browser/load_notification_details.h',
       'public/browser/local_storage_usage_info.cc',
       'public/browser/local_storage_usage_info.h',
       'public/browser/location_provider.h',
       'public/browser/media_capture_devices.h',
       'public/browser/media_device_id.cc',
       'public/browser/media_device_id.h',
+      'public/browser/message_port_provider.h',
       'public/browser/native_web_keyboard_event.h',
       'public/browser/navigation_controller.cc',
       'public/browser/navigation_controller.h',
       'public/browser/navigation_details.cc',
       'public/browser/navigation_details.h',
       'public/browser/navigation_entry.h',
       'public/browser/navigation_type.h',
       'public/browser/notification_details.h',
       'public/browser/notification_observer.h',
       'public/browser/notification_registrar.cc',
@@ skipping 749 matching lines @@
       'browser/media/midi_host.cc',
       'browser/media/midi_host.h',
       'browser/media/webrtc_identity_store.cc',
       'browser/media/webrtc_identity_store.h',
       'browser/media/webrtc_identity_store_backend.cc',
       'browser/media/webrtc_identity_store_backend.h',
       'browser/manifest/manifest_manager_host.cc',
       'browser/manifest/manifest_manager_host.h',
       'browser/message_port_message_filter.cc',
       'browser/message_port_message_filter.h',
+      'browser/message_port_provider.cc',
       'browser/message_port_service.cc',
       'browser/message_port_service.h',
       'browser/mime_registry_message_filter.cc',
       'browser/mime_registry_message_filter.h',
       'browser/mojo/mojo_application_host.cc',
       'browser/mojo/mojo_application_host.h',
       'browser/mojo/service_registry_android.cc',
       'browser/mojo/service_registry_android.h',
       'browser/net/browser_online_state_observer.cc',
       'browser/net/browser_online_state_observer.h',
@@ skipping 1010 matching lines @@
       'sources': [
         'browser/media/cdm/browser_cdm_manager.cc',
         'browser/media/cdm/browser_cdm_manager.h',
         # This works on Android because enable_browser_cdms==1 on Android.
         'browser/media/media_web_contents_observer.cc',
         'browser/media/media_web_contents_observer.h',
       ],
     }],
   ],
 }