Added empty directory with myself as owner for new mixer.

webrtc/modules/BUILD.gn

 # Copyright (c) 2016 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")
 import("audio_coding/audio_coding.gni")
 import("//testing/test.gni")
 
 declare_args() {
   # Desktop capturer is supported only on Windows, OSX and Linux.
   rtc_desktop_capture_supported = is_win || is_mac || is_linux
 }
 
 group("modules") {
   deps = [
     "audio_coding",
     "audio_conference_mixer",
     "audio_device",
+    "audio_mixer",
     "audio_processing",
     "bitrate_controller",
     "desktop_capture",
     "media_file",
     "rtp_rtcp",
     "utility",
     "video_coding",
     "video_processing",
   ]
 }
@@ skipping 498 matching lines @@
         "audio_device/ios/objc/RTCAudioSessionTest.mm",
         "video_coding/codecs/h264/h264_video_toolbox_nalu_unittest.cc",
       ]
 
       ldflags = [ "-ObjC" ]
 
       # TODO(kjellander): Mac bundle files.
     }
   }
 }