Some fixups for AudioController and unit tests

media/audio/linux/audio_manager_linux.cc

 // Copyright (c) 2006-2009 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/audio_manager_linux.h"
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "media/audio/fake_audio_output_stream.h"
@@ skipping 41 matching lines @@
   active_streams_[stream] = scoped_refptr<AlsaPcmOutputStream>(stream);
   return stream;
 }
 
 AudioManagerLinux::AudioManagerLinux()
     : audio_thread_("AudioThread"),
       initialized_(false) {
 }
 
 AudioManagerLinux::~AudioManagerLinux() {
+  // Make sure we stop the thread first. If we let the default destructor to
+  // destruct the members, we may destroy audio streams before stopping the
+  // thread, resulting an unexpected behavior.
+  // This way we make sure activities of the audio streams are all stopped
+  // before we destroy them.
+  audio_thread_.Stop();
   active_streams_.clear();
 }
 
 void AudioManagerLinux::Init() {
   initialized_ = audio_thread_.Start();
   wrapper_.reset(new AlsaWrapper());
 }
 
 void AudioManagerLinux::MuteAll() {
   NOTIMPLEMENTED();
@@ skipping 17 matching lines @@
 }
 
 AudioManager* AudioManager::GetAudioManager() {
   if (!g_audio_manager) {
     g_audio_manager = new AudioManagerLinux();
     g_audio_manager->Init();
     base::AtExitManager::RegisterCallback(&DestroyAudioManagerLinux, NULL);
   }
   return g_audio_manager;
 }