Restores larger output buffer size when output stream requiring smaller size is closed

media/audio/mac/audio_auhal_mac.cc

Index: media/audio/mac/audio_auhal_mac.cc
diff --git a/media/audio/mac/audio_auhal_mac.cc b/media/audio/mac/audio_auhal_mac.cc
index d71673fd12ae517dd61f0fdedabda64d2e7e4077..8bb62e809ecb08be16817bb5389d1b44d657a506 100644
--- a/media/audio/mac/audio_auhal_mac.cc
+++ b/media/audio/mac/audio_auhal_mac.cc
@@ -44,6 +44,7 @@ AUHALStream::AUHALStream(AudioManagerMac* manager,
       params_(params),
       output_channels_(params_.channels()),
       number_of_frames_(params_.frames_per_buffer()),
+      actual_io_buffer_frame_size_(0),
       number_of_frames_requested_(0),
       source_(NULL),
       device_(device),
@@ -115,6 +116,12 @@ bool AUHALStream::Open() {
   if (configured)
     hardware_latency_frames_ = GetHardwareLatency();
 
+#if !defined(NDEBUG)
+  // Print a list of all existing output streams and there current buffer size
+  // state (required and actual). Does nothing in Release builds.
+  manager_->PrintOutputBufferSizes();
+#endif
+
   return configured;
 }
 
@@ -175,6 +182,7 @@ void AUHALStream::Stop() {
   if (stopped_)
     return;
   DVLOG(1) << "Stop";
+  DVLOG(2) << "number_of_frames: " << number_of_frames_;
   OSStatus result = AudioOutputUnitStop(audio_unit_);
   OSSTATUS_DLOG_IF(ERROR, result != noErr, result)
       << "AudioOutputUnitStop() failed.";
@@ -217,13 +225,16 @@ OSStatus AUHALStream::Render(
       // any further changes will be ignored. It would be nice to have all
       // changes reflected in UMA stats.
       number_of_frames_requested_ = number_of_frames;
+      actual_io_buffer_frame_size_ = number_of_frames;
       DVLOG(1) << "Audio frame size changed from " << number_of_frames_
-               << " to " << number_of_frames
-               << "; adding FIFO to compensate.";
+               << " to " << number_of_frames << " adding FIFO to compensate.";
       audio_fifo_.reset(new AudioPullFifo(
           output_channels_,
           number_of_frames_,
           base::Bind(&AUHALStream::ProvideInput, base::Unretained(this))));
+#if !defined(NDEBUG)
+      manager_->PrintOutputBufferSizes();
+#endif
     }
   }
 
@@ -512,6 +523,26 @@ bool AUHALStream::ConfigureAUHAL() {
     return false;
   }
 
+  // Get the actual number of frames in the IO buffers after the audio manager
+  // has tried to set the requested size. We could use |io_buffer_frame_size|
+  // here instead of doing these extra steps but I prefer to play it safe and
+  // to ensure that the change done by the audio manager is really active.
+  // TODO(henrika): it might be possible to remove this part.
+  UInt32 actual_io_buffer_frame_size;
+  UInt32 property_size = sizeof(actual_io_buffer_frame_size);
+  result = AudioUnitGetProperty(
+      audio_unit_, kAudioDevicePropertyBufferFrameSize, kAudioUnitScope_Global,
+      0, &actual_io_buffer_frame_size, &property_size);
+  LOG_IF(WARNING, result != noErr)
+      << "Failed to get the actual I/O buffer size";
+  if (result == noErr) {
+    actual_io_buffer_frame_size_ = actual_io_buffer_frame_size;
+    DVLOG(1) << "actual_io_buffer_frame_size: " << actual_io_buffer_frame_size_;
+  }
+  LOG_IF(WARNING, actual_io_buffer_frame_size_ != number_of_frames_)
+      << "Failed to set the requested buffer frame size exactly";
+  DCHECK_EQ(io_buffer_frame_size, actual_io_buffer_frame_size);
+
   // Setup callback.
   AURenderCallbackStruct callback;
   callback.inputProc = InputProc;