[Chromoting] Add AudioVolumeApplier to reduce the complexity and the dependency of kChannels

remoting/host/win/BUILD.gn

 # Copyright 2016 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.
 
 import("//build/toolchain/win/midl.gni")
 import("//build/win/message_compiler.gni")
 import("//media/media_options.gni")
 import("//remoting/build/config/remoting_build.gni")
 import("//remoting/host/installer/win/generate_clsids.gni")
 
@@ skipping 60 matching lines @@
     common_controls_manifest,
     default_compatibility_manifest,
     dpi_aware_manifest,
     enable_uiaccess_require_admin_manifest,
   ]
   type = "exe"
 }
 
 source_set("win") {
   sources = [
+    "audio_volume_applier_win.cc",
+    "audio_volume_applier_win.h",
     "com_imported_mstscax.tlh",
     "com_security.cc",
     "com_security.h",
     "default_audio_device_change_detector.cc",
     "default_audio_device_change_detector.h",
     "elevation_helpers.cc",
     "elevation_helpers.h",
     "launch_process_with_token.cc",
     "launch_process_with_token.h",
     "omaha.cc",
@@ skipping 405 matching lines @@
 
   output = "$root_gen_dir/remoting/{{source_name_part}}"
 
   locale_dir = webapp_locale_dir
 
   encoding = "utf-16"
 
   locales = remoting_locales
 }
 # TODO(GYP) More Windows remoting targets from remoting_host_win.gypi