Remove voe::OutputMixer and AudioConferenceMixer.

voice_engine/BUILD.gn

 # Copyright (c) 2014 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("../webrtc.gni")
 
 rtc_static_library("voice_engine") {
   sources = [
     "channel.cc",
     "channel.h",
     "channel_manager.cc",
     "channel_manager.h",
     "channel_proxy.cc",
     "channel_proxy.h",
     "include/voe_base.h",
     "include/voe_errors.h",
     "monitor_module.h",
-    "output_mixer.cc",
-    "output_mixer.h",
     "shared_data.cc",
     "shared_data.h",
     "statistics.cc",
     "statistics.h",
     "transmit_mixer.cc",
     "transmit_mixer.h",
     "transport_feedback_packet_loss_tracker.cc",
     "transport_feedback_packet_loss_tracker.h",
     "utility.cc",
     "utility.h",
@@ skipping 33 matching lines @@
     "../api/audio_codecs:audio_codecs_api",
     "../api/audio_codecs:builtin_audio_decoder_factory",
     "../api/audio_codecs:builtin_audio_encoder_factory",
     "../audio/utility:audio_frame_operations",
     "../call:rtp_interfaces",
     "../common_audio",
     "../logging:rtc_event_log_api",
     "../modules:module_api",
     "../modules/audio_coding:audio_format_conversion",
     "../modules/audio_coding:rent_a_codec",
-    "../modules/audio_conference_mixer",
     "../modules/audio_device",
     "../modules/audio_processing",
     "../modules/bitrate_controller",
     "../modules/media_file",
     "../modules/pacing",
     "../modules/rtp_rtcp",
     "../modules/utility",
     "../rtc_base:rtc_base_approved",
     "../rtc_base:rtc_task_queue",
     "../system_wrappers",
@@ skipping 14 matching lines @@
   ]
 }
 
 if (rtc_include_tests) {
   rtc_test("voice_engine_unittests") {
     deps = [
       ":voice_engine",
       "../common_audio",
       "../modules:module_api",
       "../modules/audio_coding",
-      "../modules/audio_conference_mixer",
       "../modules/audio_device",
       "../modules/audio_processing",
       "../modules/media_file",
       "../modules/rtp_rtcp",
       "../modules/utility",
       "../modules/video_capture:video_capture",
       "../rtc_base:rtc_base_approved",
       "../rtc_base:rtc_base_tests_utils",
       "../system_wrappers",
       "../test:test_common",
@@ skipping 28 matching lines @@
         "/wd4373",  # Virtual function override.
       ]
     }
 
     if (!build_with_chromium && is_clang) {
       # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
       suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
     }
   }
 }