[Cast] In Audio/VideoSender, drop frames when too-long a duration is in-flight.

media/cast/cast.gyp

 # Copyright 2013 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.
 
 {
   'variables': {
     'include_tests%': 1,
     'chromium_code': 1,
   },
   'conditions': [
@@ skipping 136 matching lines @@
         'sender/audio_sender.h',
         'sender/audio_sender.cc',
         'sender/congestion_control.h',
         'sender/congestion_control.cc',
         'sender/external_video_encoder.h',
         'sender/external_video_encoder.cc',
         'sender/fake_software_video_encoder.h',
         'sender/fake_software_video_encoder.cc',
         'sender/frame_sender.cc',
         'sender/frame_sender.h',
-        'sender/rtp_timestamp_helper.cc',
-        'sender/rtp_timestamp_helper.h',
         'sender/software_video_encoder.h',
         'sender/video_encoder.h',
         'sender/video_encoder_impl.h',
         'sender/video_encoder_impl.cc',
         'sender/video_sender.h',
         'sender/video_sender.cc',
         'sender/vp8_encoder.cc',
         'sender/vp8_encoder.h',
       ], # source
     },
@@ skipping 32 matching lines @@
         'net/rtp/rtp_packetizer.cc',
         'net/rtp/rtp_packetizer.h',
         'net/rtp/rtp_sender.cc',
         'net/rtp/rtp_sender.h',
         'net/udp_transport.cc',
         'net/udp_transport.h',
       ], # source
     },
   ],
 }