arc-bridge: Split ArcBridgeService to common part and IPC based impl.

components/arc.gypi

 # Copyright 2015 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.
 
 {
   'targets': [
     {
       # GN version: //components/arc
       'target_name': 'arc',
       'type': 'static_library',
       'include_dirs': [
         '..',
       ],
       'dependencies': [
         '../base/base.gyp:base',
         '../chromeos/chromeos.gyp:chromeos',
         '../ipc/ipc.gyp:ipc',
       ],
       'sources': [
         'arc/arc_bridge_service.cc',
         'arc/arc_bridge_service.h',
+        'arc/arc_bridge_service_impl.cc',
+        'arc/arc_bridge_service_impl.h',
         'arc/common/arc_host_messages.h',
         'arc/common/arc_instance_messages.h',
         'arc/common/arc_message_generator.cc',
         'arc/common/arc_message_generator.h',
       ],
     },
   ],
 }