Add mojo interface+impl for audio stream control.

media/mojo/BUILD.gn

 # Copyright 2014 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("//testing/test.gni")
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "clients/mojo_audio_decoder_unittest.cc",
     "clients/mojo_cdm_unittest.cc",
     "clients/mojo_decryptor_unittest.cc",
     "clients/mojo_renderer_unittest.cc",
     "common/media_type_converters_unittest.cc",
     "common/mojo_decoder_buffer_converter_unittest.cc",
     "common/mojo_shared_buffer_video_frame_unittest.cc",
+    "services/mojo_audio_output_stream_unittest.cc",
     "services/mojo_cdm_allocator_unittest.cc",
   ]
 
   deps = [
     "//base",
     "//base/test:test_support",
     "//media",
     "//media:cdm_api",
     "//media/base:test_support",
     "//media/mojo/clients",
@@ skipping 14 matching lines @@
       "/ignore:4217",
       "/ignore:4049",
     ]
   }
 
   deps = [
     ":unit_tests",
     "//mojo/edk/test:run_all_unittests",
   ]
 }