Add an ALSA output to the motown audio server.

services/media/audio/platform/stubs/alsa_output_stub.cc

Index: services/media/audio/platform/stubs/alsa_output_stub.cc
diff --git a/services/media/audio/platform/stubs/alsa_output_stub.cc b/services/media/audio/platform/stubs/alsa_output_stub.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6bf4877fe4fcf66c04edc505c4b1183cee156854
--- /dev/null
+++ b/services/media/audio/platform/stubs/alsa_output_stub.cc
@@ -0,0 +1,17 @@
+// 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.
+
+#include "services/media/audio/fwd_decls.h"
+
+namespace mojo {
+namespace media {
+namespace audio {
+
+AudioOutputPtr CreateDefaultAlsaOutput(AudioOutputManager* manager) {
+  return nullptr;
+}
+
+}  // namespace audio
+}  // namespace media
+}  // namespace mojo