Remove voe::OutputMixer and AudioConferenceMixer.

PRESUBMIT.py

 # Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import json
 import os
 import re
 import subprocess
 import sys
 from collections import defaultdict
 
 
 # Files and directories that are *skipped* by cpplint in the presubmit script.
 CPPLINT_BLACKLIST = [
   'api/video_codecs/video_decoder.h',
   'common_types.cc',
   'common_types.h',
   'examples/objc',
   'media',
   'modules/audio_coding',
-  'modules/audio_conference_mixer',
   'modules/audio_device',
   'modules/audio_processing',
   'modules/desktop_capture',
   'modules/include/module_common_types.h',
   'modules/media_file',
   'modules/utility',
   'modules/video_capture',
   'p2p',
   'pc',
   'rtc_base',
@@ skipping 31 matching lines @@
   'media',
   'modules/audio_device/include',
   'pc',
 )
 
 # These directories should not be used but are maintained only to avoid breaking
 # some legacy downstream code.
 LEGACY_API_DIRS = (
   'common_audio/include',
   'modules/audio_coding/include',
-  'modules/audio_conference_mixer/include',
   'modules/audio_processing/include',
   'modules/bitrate_controller/include',
   'modules/congestion_controller/include',
   'modules/include',
   'modules/remote_bitrate_estimator/include',
   'modules/rtp_rtcp/include',
   'modules/rtp_rtcp/source',
   'modules/utility/include',
   'modules/video_coding/codecs/h264/include',
   'modules/video_coding/codecs/i420/include',
@@ skipping 650 matching lines @@
   results = []
   source_file_filter = lambda x: input_api.FilterSourceFile(
       x, white_list=(r'.+\.proto$',))
   for f in input_api.AffectedSourceFiles(source_file_filter):
     file_path = f.LocalPath()
     with open(file_path) as f:
       lines = f.readlines()
       if len(lines) > 0 and not lines[-1].endswith('\n'):
         results.append(output_api.PresubmitError(error_msg.format(file_path)))
   return results