Add an ALSA output to the motown audio server.

services/media/audio/platform/generic/mixer.cc

 // 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 "base/logging.h"
 #include "services/media/audio/platform/generic/mixer.h"
 #include "services/media/audio/platform/generic/mixers/no_op.h"
 #include "services/media/audio/platform/generic/mixers/point_sampler.h"
 
 namespace mojo {
 namespace media {
 namespace audio {
 
 Mixer::Mixer() {}
 Mixer::~Mixer() {}
 
 MixerPtr Mixer::Select(const LpcmMediaTypeDetailsPtr& src_format,
                        const LpcmMediaTypeDetailsPtr& dst_format) {
   // We should always have a source format.
   DCHECK(src_format);
 
   // If we don't have a destination format, just stick with no-op.  This is
   // probably the ThrottleOutput we are picking a mixer for.
   if (!dst_format) { return MixerPtr(new mixers::NoOp()); }
 
   return mixers::PointSampler::Select(src_format, dst_format);
 }
 
 }  // namespace audio
 }  // namespace media
 }  // namespace mojo