Deliver RenderCallbackErrors even when mixer inputs are paused.

media/base/audio_renderer_mixer.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/base/audio_renderer_mixer.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 
@@ skipping 13 matching lines @@
   audio_sink_->Initialize(output_params, this);
   audio_sink_->Start();
 }
 
 AudioRendererMixer::~AudioRendererMixer() {
   // AudioRendererSinks must be stopped before being destructed.
   audio_sink_->Stop();
 
   // Ensures that all mixer inputs have stopped themselves prior to destruction
   // and have called RemoveMixerInput().
-  DCHECK_EQ(mixer_inputs_.size(), 0U);
+  DCHECK_EQ(error_callbacks_.size(), 0U);
 }
 
-void AudioRendererMixer::AddMixerInput(AudioConverter::InputCallback* input,
-                                       const base::Closure& error_cb) {
-  base::AutoLock auto_lock(mixer_inputs_lock_);
-
+void AudioRendererMixer::AddMixerInput(AudioConverter::InputCallback* input) {
+  base::AutoLock auto_lock(lock_);
   if (!playing_) {
     playing_ = true;
     last_play_time_ = base::TimeTicks::Now();
     audio_sink_->Play();
   }
 
-  DCHECK(mixer_inputs_.find(input) == mixer_inputs_.end());
-  mixer_inputs_[input] = error_cb;
+  DCHECK(error_callbacks_.find(input) != error_callbacks_.end());
   audio_converter_.AddInput(input);
 }
 
 void AudioRendererMixer::RemoveMixerInput(
     AudioConverter::InputCallback* input) {
-  base::AutoLock auto_lock(mixer_inputs_lock_);
+  base::AutoLock auto_lock(lock_);
   audio_converter_.RemoveInput(input);
+}
 
-  DCHECK(mixer_inputs_.find(input) != mixer_inputs_.end());
-  mixer_inputs_.erase(input);
+void AudioRendererMixer::RegisterErrorCallback(
+    AudioConverter::InputCallback* input,

[scherkus (not reviewing), 2014/06/03 02:01:31]

would using a map/list/vector work? there doesn't seem to be a real need to tie
|input| with the callback

do we expect the size of these data structures to be really large?

[DaleCurtis, 2014/06/03 20:26:19]

This is using a map so I'm not sure what you're asking.  At the time I wrote
this, I ran into issues putting callbacks in a list/vector and then finding them
again since each placement makes a copy.  It seems to work correctly now though,
so I've switched this to a list and added a note that calls must specify the
same callback to Add/Remove.

+    const base::Closure& error_cb) {
+  base::AutoLock auto_lock(lock_);
+  DCHECK(error_callbacks_.find(input) == error_callbacks_.end());
+  error_callbacks_[input] = error_cb;
+}
+
+void AudioRendererMixer::UnregisterErrorCallback(
+    AudioConverter::InputCallback* input) {
+  base::AutoLock auto_lock(lock_);
+  DCHECK(error_callbacks_.find(input) != error_callbacks_.end());
+  error_callbacks_.erase(input);
 }
 
 int AudioRendererMixer::Render(AudioBus* audio_bus,
                                int audio_delay_milliseconds) {
-  base::AutoLock auto_lock(mixer_inputs_lock_);
+  base::AutoLock auto_lock(lock_);
 
   // If there are no mixer inputs and we haven't seen one for a while, pause the
   // sink to avoid wasting resources when media elements are present but remain
   // in the pause state.
   const base::TimeTicks now = base::TimeTicks::Now();
-  if (!mixer_inputs_.empty()) {
+  if (!audio_converter_.empty()) {
     last_play_time_ = now;
   } else if (now - last_play_time_ >= pause_delay_ && playing_) {
     audio_sink_->Pause();
     playing_ = false;
   }
 
   audio_converter_.ConvertWithDelay(
       base::TimeDelta::FromMilliseconds(audio_delay_milliseconds), audio_bus);
   return audio_bus->frames();
 }
 
 void AudioRendererMixer::OnRenderError() {
-  base::AutoLock auto_lock(mixer_inputs_lock_);
+  base::AutoLock auto_lock(lock_);
 
   // Call each mixer input and signal an error.
-  for (AudioRendererMixerInputSet::iterator it = mixer_inputs_.begin();
-       it != mixer_inputs_.end(); ++it) {
+  for (AudioRendererMixerErrorCallbackMap::iterator it =
+           error_callbacks_.begin();
+       it != error_callbacks_.end();
+       ++it) {
     it->second.Run();
   }
 }
 
 }  // namespace media