Abort expensive AudioManager methods once shutdown starts.

media/audio/audio_manager_base.cc

Index: media/audio/audio_manager_base.cc
diff --git a/media/audio/audio_manager_base.cc b/media/audio/audio_manager_base.cc
index 0b192523d4b3f65e624246b3c7b712053288a7da..f2ae2540f732b789d0e55abce906525ef78e6b8a 100644
--- a/media/audio/audio_manager_base.cc
+++ b/media/audio/audio_manager_base.cc
@@ -81,7 +81,8 @@ AudioManagerBase::AudioManagerBase(AudioLogFactory* audio_log_factory)
       output_listeners_(
           ObserverList<AudioDeviceListener>::NOTIFY_EXISTING_ONLY),
       audio_thread_("AudioThread"),
-      audio_log_factory_(audio_log_factory) {
+      audio_log_factory_(audio_log_factory),
+      in_shutdown_(0) {
 #if defined(OS_WIN)
   audio_thread_.init_com_with_mta(true);
 #elif defined(OS_MACOSX)
@@ -138,6 +139,8 @@ AudioOutputStream* AudioManagerBase::MakeAudioOutputStream(
   // TODO(miu): Fix ~50 call points across several unit test modules to call
   // this method on the audio thread, then uncomment the following:
   // DCHECK(task_runner_->BelongsToCurrentThread());
+  if (base::AtomicRefCountIsOne(&in_shutdown_))
+    return NULL;
 
   if (!params.IsValid()) {
     DLOG(ERROR) << "Audio parameters are invalid";
@@ -187,6 +190,8 @@ AudioInputStream* AudioManagerBase::MakeAudioInputStream(
   // TODO(miu): Fix ~20 call points across several unit test modules to call
   // this method on the audio thread, then uncomment the following:
   // DCHECK(task_runner_->BelongsToCurrentThread());
+  if (base::AtomicRefCountIsOne(&in_shutdown_))
+    return NULL;
 
   if (!params.IsValid() || (params.channels() > kMaxInputChannels) ||
       device_id.empty()) {
@@ -228,6 +233,8 @@ AudioOutputStream* AudioManagerBase::MakeAudioOutputStreamProxy(
     const AudioParameters& params,
     const std::string& device_id) {
   DCHECK(task_runner_->BelongsToCurrentThread());
+  if (base::AtomicRefCountIsOne(&in_shutdown_))
+    return NULL;
 
   // If the caller supplied an empty device id to select the default device,
   // we fetch the actual device id of the default device so that the lookup
@@ -322,6 +329,9 @@ void AudioManagerBase::ReleaseInputStream(AudioInputStream* stream) {
 }
 
 void AudioManagerBase::Shutdown() {
+  DCHECK(base::AtomicRefCountIsZero(&in_shutdown_));
+  base::AtomicRefCountInc(&in_shutdown_);
+
   // Only true when we're sharing the UI message loop with the browser.  The UI
   // loop is no longer running at this time and browser destruction is imminent.
   if (task_runner_->BelongsToCurrentThread()) {
@@ -337,6 +347,7 @@ void AudioManagerBase::Shutdown() {
 
 void AudioManagerBase::ShutdownOnAudioThread() {
   DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(base::AtomicRefCountIsOne(&in_shutdown_));
 
   AudioOutputDispatchers::iterator it = output_dispatchers_.begin();
   for (; it != output_dispatchers_.end(); ++it) {
@@ -369,6 +380,8 @@ void AudioManagerBase::RemoveOutputDeviceChangeListener(
 
 void AudioManagerBase::NotifyAllOutputDeviceChangeListeners() {
   DCHECK(task_runner_->BelongsToCurrentThread());
+  if (base::AtomicRefCountIsOne(&in_shutdown_))
+    return;
   DVLOG(1) << "Firing OnDeviceChange() notifications.";
   FOR_EACH_OBSERVER(AudioDeviceListener, output_listeners_, OnDeviceChange());
 }