Detect errors in audio output and report them upstream.

media/audio/linux/alsa_output.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.
 //
 // THREAD SAFETY
 //
 // AlsaPcmOutputStream object is *not* thread-safe and should only be used
 // from the audio thread.  We DCHECK on this assumption whenever we can.
 //
 // SEMANTICS OF Close()
@@ skipping 250 matching lines @@
     playback_handle_ = alsa_util::OpenPlaybackDevice(wrapper_,
                                                      device_name_.c_str(),
                                                      channels_, sample_rate_,
                                                      pcm_format_,
                                                      latency_micros_);
   }
 
   // Finish initializing the stream if the device was opened successfully.
   if (playback_handle_ == NULL) {
     stop_stream_ = true;
+    TransitionTo(kInError);
+    return false;
   } else {
     bytes_per_output_frame_ = should_downmix_ ? 2 * bytes_per_sample_ :
         bytes_per_frame_;
     uint32 output_packet_size = frames_per_packet_ * bytes_per_output_frame_;
     buffer_.reset(new media::SeekableBuffer(0, output_packet_size));
 
     // Get alsa buffer size.
     snd_pcm_uframes_t buffer_size;
     snd_pcm_uframes_t period_size;
     int error = wrapper_->PcmGetParams(playback_handle_, &buffer_size,
@@ skipping 558 matching lines @@
   if (source_callback_)
     source_callback_->OnError(this, code);
 }
 
 // Changes the AudioSourceCallback to proxy calls to.  Pass in NULL to
 // release ownership of the currently registered callback.
 void AlsaPcmOutputStream::set_source_callback(AudioSourceCallback* callback) {
   DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
   source_callback_ = callback;
 }