Move Alsa device opening into the audio thread, and add in support for multi-channel audio.

media/audio/linux/alsa_wrapper.cc

 // Copyright (c) 2009 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 "media/audio/linux/alsa_wrapper.h"
 
 #include <alsa/asoundlib.h>
 
 AlsaWrapper::AlsaWrapper() {
 }
 
 AlsaWrapper::~AlsaWrapper() {
 }
 
 int AlsaWrapper::PcmOpen(snd_pcm_t** handle, const char* name,
                          snd_pcm_stream_t stream, int mode) {
   return snd_pcm_open(handle, name, stream, mode);
 }
 
+int AlsaWrapper::DeviceNameHint(int card, const char* iface, void*** hints) {
+  return snd_device_name_hint(card, iface, hints);
+}
+
+char* AlsaWrapper::DeviceNameGetHint(const void* hint, const char* id) {
+  return snd_device_name_get_hint(hint, id);
+}
+
+int AlsaWrapper::DeviceNameFreeHint(void** hints) {
+  return snd_device_name_free_hint(hints);
+}
+
 int AlsaWrapper::PcmClose(snd_pcm_t* handle) {
   return snd_pcm_close(handle);
 }
 
 int AlsaWrapper::PcmPrepare(snd_pcm_t* handle) {
   return snd_pcm_prepare(handle);
 }
 
 int AlsaWrapper::PcmDrop(snd_pcm_t* handle) {
   return snd_pcm_drop(handle);
@@ skipping 25 matching lines @@
                             soft_resample, latency);
 }
 
 snd_pcm_sframes_t AlsaWrapper::PcmAvailUpdate(snd_pcm_t* handle) {
   return snd_pcm_avail_update(handle);
 }
 
 const char* AlsaWrapper::StrError(int errnum) {
   return snd_strerror(errnum);
 }