Implement hook to change audio output device for PulseAudio.

media/audio/pulse/pulse_util.cc

 // Copyright (c) 2012 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/pulse/pulse_util.h"
 
 #include "base/logging.h"
 #include "base/time/time.h"
 #include "media/audio/audio_manager_base.h"
 #include "media/audio/audio_parameters.h"
@@ skipping 187 matching lines @@
     pa_threaded_mainloop_wait(mainloop);
   }
 
   return true;
 }
 
 bool CreateOutputStream(pa_threaded_mainloop** mainloop,
                         pa_context** context,
                         pa_stream** stream,
                         const AudioParameters& params,
+                        const std::string& device_id,
                         pa_stream_notify_cb_t stream_callback,
                         pa_stream_request_cb_t write_callback,
                         void* user_data) {
   DCHECK(!*mainloop);
   DCHECK(!*context);
 
   *mainloop = pa_threaded_mainloop_new();
   RETURN_ON_FAILURE(*mainloop, "Failed to create PulseAudio main loop.");
 
   pa_mainloop_api* pa_mainloop_api = pa_threaded_mainloop_get_api(*mainloop);
@@ skipping 62 matching lines @@
   pa_buffer_attributes.minreq = params.GetBytesPerBuffer();
   pa_buffer_attributes.prebuf = static_cast<uint32_t>(-1);
   pa_buffer_attributes.tlength = params.GetBytesPerBuffer() * 3;
   pa_buffer_attributes.fragsize = static_cast<uint32_t>(-1);
 
   // Connect playback stream.  Like pa_buffer_attr, the pa_stream_flags have a
   // huge impact on the performance of the stream and were chosen through trial
   // and error.
   RETURN_ON_FAILURE(
       pa_stream_connect_playback(
-          *stream, NULL, &pa_buffer_attributes,
+          *stream,
+          device_id == AudioManagerBase::kDefaultDeviceId ?
+              NULL : device_id.c_str(),
+          &pa_buffer_attributes,
           static_cast<pa_stream_flags_t>(
               PA_STREAM_INTERPOLATE_TIMING | PA_STREAM_ADJUST_LATENCY |
               PA_STREAM_AUTO_TIMING_UPDATE | PA_STREAM_NOT_MONOTONIC |
               PA_STREAM_START_CORKED),
-          NULL, NULL) == 0,
+          NULL,
+          NULL) == 0,
       "pa_stream_connect_playback FAILED ");
 
   // Wait for the stream to be ready.
   while (true) {
     pa_stream_state_t stream_state = pa_stream_get_state(*stream);
     RETURN_ON_FAILURE(
         PA_STREAM_IS_GOOD(stream_state), "Invalid PulseAudio stream state");
     if (stream_state == PA_STREAM_READY)
       break;
     pa_threaded_mainloop_wait(*mainloop);
   }
 
   return true;
 }
 
 #undef RETURN_ON_FAILURE
 
 }  // namespace pulse
 
 }  // namespace media