[Chromecast] Add a return value after NOTREACHED in tests.

chromecast/media/BUILD.gn

 # Copyright 2015 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("//chromecast/chromecast.gni")
 import("//testing/test.gni")
 
 group("media") {
   deps = [
     "//chromecast/media/audio",
     "//chromecast/media/base",
     "//chromecast/media/cdm",
     "//chromecast/media/cma",
   ]
 }
 
 test("cast_media_unittests") {
   sources = [
+    "audio/cast_audio_output_stream_unittest.cc",

[alokp, 2015/09/21 19:38:35]

Is this required because we do not have media/BUILD.gn downstream? Do you want
to delete audio:test_support in that case? It is dead code now.

     "cma/backend/audio_video_pipeline_device_unittest.cc",
     "cma/base/balanced_media_task_runner_unittest.cc",
     "cma/base/buffering_controller_unittest.cc",
     "cma/base/buffering_frame_provider_unittest.cc",
     "cma/filters/demuxer_stream_adapter_unittest.cc",
     "cma/filters/multi_demuxer_stream_adapter_unittest.cc",
     "cma/ipc/media_message_fifo_unittest.cc",
     "cma/ipc/media_message_unittest.cc",
     "cma/ipc_streamer/av_streamer_unittest.cc",
     "cma/pipeline/audio_video_pipeline_impl_unittest.cc",
@@ skipping 41 matching lines @@
       "$libcast_media_path:libcast_media_1.0",
     ]
   }
 }
 
 # TODO(slan): delete this target once Chromecast M44/earlier is obsolete.
 # See: b/21639416
 shared_library("libffmpegsumo") {
   output_name = "libffmpegsumo"
 }