Update DCHECKs in AlsaPcmOutputStream to account for NULL message loop.

TBR=xians

Review URL: https://chromiumcodereview.appspot.com/9403027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@122146 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 23 insertions, 14 deletions

diff --git a/media/audio/linux/alsa_output.cc b/media/audio/linux/alsa_output.cc
index 0cc5280..0cd2d0c 100644
--- a/media/audio/linux/alsa_output.cc
+++ b/media/audio/linux/alsa_output.cc
@@ -204,7 +204,7 @@ AlsaPcmOutputStream::AlsaPcmOutputStream(const std::string& device_name,
       state_(kCreated),
       volume_(1.0f),
       source_callback_(NULL) {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   // Sanity check input values.
   if ((params.sample_rate > kAlsaMaxSampleRate) || (params.sample_rate <= 0)) {
@@ -233,7 +233,7 @@ AlsaPcmOutputStream::~AlsaPcmOutputStream() {
 }
 
 bool AlsaPcmOutputStream::Open() {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   if (state() == kInError)
     return false;
@@ -293,7 +293,7 @@ bool AlsaPcmOutputStream::Open() {
 }
 
 void AlsaPcmOutputStream::Close() {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   // Sanity check that the transition occurs correctly.  It is safe to
   // continue anyways because all operations for closing are idempotent.
@@ -322,7 +322,7 @@ void AlsaPcmOutputStream::Close() {
 }
 
 void AlsaPcmOutputStream::Start(AudioSourceCallback* callback) {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   CHECK(callback);
 
@@ -361,7 +361,7 @@ void AlsaPcmOutputStream::Start(AudioSourceCallback* callback) {
 }
 
 void AlsaPcmOutputStream::Stop() {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   // Reset the callback, so that it is not called anymore.
   set_source_callback(NULL);
@@ -370,19 +370,19 @@ void AlsaPcmOutputStream::Stop() {
 }
 
 void AlsaPcmOutputStream::SetVolume(double volume) {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   volume_ = static_cast<float>(volume);
 }
 
 void AlsaPcmOutputStream::GetVolume(double* volume) {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   *volume = volume_;
 }
 
 void AlsaPcmOutputStream::BufferPacket(bool* source_exhausted) {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   // If stopped, simulate a 0-length packet.
   if (stop_stream_) {
@@ -473,7 +473,7 @@ void AlsaPcmOutputStream::BufferPacket(bool* source_exhausted) {
 }
 
 void AlsaPcmOutputStream::WritePacket() {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   // If the device is in error, just eat the bytes.
   if (stop_stream_) {
@@ -537,7 +537,7 @@ void AlsaPcmOutputStream::WritePacket() {
 }
 
 void AlsaPcmOutputStream::WriteTask() {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   if (stop_stream_)
     return;
@@ -553,7 +553,7 @@ void AlsaPcmOutputStream::WriteTask() {
 }
 
 void AlsaPcmOutputStream::ScheduleNextWrite(bool source_exhausted) {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   if (stop_stream_)
     return;
@@ -695,7 +695,7 @@ snd_pcm_sframes_t AlsaPcmOutputStream::GetCurrentDelay() {
 }
 
 snd_pcm_sframes_t AlsaPcmOutputStream::GetAvailableFrames() {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   if (stop_stream_)
     return 0;
@@ -809,7 +809,7 @@ bool AlsaPcmOutputStream::CanTransitionTo(InternalState to) {
 
 AlsaPcmOutputStream::InternalState
 AlsaPcmOutputStream::TransitionTo(InternalState to) {
-  DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(IsOnAudioThread());
 
   if (!CanTransitionTo(to)) {
     NOTREACHED() << "Cannot transition from: " << state_ << " to: " << to;
@@ -824,6 +824,11 @@ AlsaPcmOutputStream::InternalState AlsaPcmOutputStream::state() {
   return state_;
 }
 
+bool AlsaPcmOutputStream::IsOnAudioThread() const {
+  return !manager_->GetMessageLoop() ||
+         manager_->GetMessageLoop()->BelongsToCurrentThread();
+}
+
 uint32 AlsaPcmOutputStream::RunDataCallback(uint8* dest,
                                             uint32 max_size,
                                             AudioBuffersState buffers_state) {
@@ -843,6 +848,6 @@ void AlsaPcmOutputStream::RunErrorCallback(int 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());
+  DCHECK(IsOnAudioThread());
   source_callback_ = callback;
 }
diff --git a/media/audio/linux/alsa_output.h b/media/audio/linux/alsa_output.h
index 54d38a0..ee257eb 100644
--- a/media/audio/linux/alsa_output.h
+++ b/media/audio/linux/alsa_output.h
@@ -139,6 +139,10 @@ class MEDIA_EXPORT AlsaPcmOutputStream : public AudioOutputStream {
   InternalState TransitionTo(InternalState to);
   InternalState state();
 
+  // Returns true when we're on the audio thread or if the audio thread's
+  // message loop is NULL (which will happen during shutdown).
+  bool IsOnAudioThread() const;
+
   // API for Proxying calls to the AudioSourceCallback provided during
   // Start().
   //