Add AudioSendStream to Call.

webrtc/audio/BUILD.gn

 # Copyright (c) 2015 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("../build/webrtc.gni")
 
 source_set("audio") {
   sources = [
     "audio_receive_stream.cc",
     "audio_receive_stream.h",
+    "audio_send_stream.cc",
+    "audio_send_stream.h",
   ]
 
   configs += [ "..:common_config" ]
   public_configs = [ "..:common_inherited_config" ]
 
   if (is_clang) {
     # Suppress warnings from Chrome's Clang plugins.
     # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
     configs -= [ "//build/config/clang:find_bad_constructs" ]
   }
 
   deps = [
     "..:webrtc_common",
     "../voice_engine",
     "../system_wrappers",
   ]
 }