Cast: Don't create threads for each CastSessionDelegate

chrome/chrome_renderer.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.
 
 {
   'targets': [
     {
       'target_name': 'renderer',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 149 matching lines @@
         'renderer/loadtimes_extension_bindings.cc',
         'renderer/loadtimes_extension_bindings.h',
         'renderer/media/cast_rtp_stream.cc',
         'renderer/media/cast_rtp_stream.h',
         'renderer/media/cast_ipc_dispatcher.cc',
         'renderer/media/cast_ipc_dispatcher.h',
         'renderer/media/cast_session.cc',
         'renderer/media/cast_session.h',
         'renderer/media/cast_session_delegate.cc',
         'renderer/media/cast_session_delegate.h',
+        'renderer/media/cast_threads.cc',
+        'renderer/media/cast_threads.h',
         'renderer/media/cast_transport_sender_ipc.cc',
         'renderer/media/cast_transport_sender_ipc.h',
         'renderer/media/cast_udp_transport.cc',
         'renderer/media/cast_udp_transport.h',
         'renderer/media/chrome_key_systems.cc',
         'renderer/media/chrome_key_systems.h',
         'renderer/media/chrome_webrtc_log_message_delegate.cc',
         'renderer/media/chrome_webrtc_log_message_delegate.h',
         'renderer/media/webrtc_logging_message_filter.cc',
         'renderer/media/webrtc_logging_message_filter.h',
@@ skipping 292 matching lines @@
         }],
         ['enable_printing!=0', {
           'dependencies': [
             '../printing/printing.gyp:printing',
           ],
         }],
       ],
     },
   ],
 }