(Relanding) Restores larger output buffer size when output stream requiring smaller size is closed

media/audio/mac/audio_auhal_mac.cc

 // Copyright 2013 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/mac/audio_auhal_mac.h"
 
 #include <CoreServices/CoreServices.h>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 104 matching lines @@
   if (configured)
     hardware_latency_frames_ = GetHardwareLatency();
 
   return configured;
 }
 
 void AUHALStream::Close() {
   DCHECK(thread_checker_.CalledOnValidThread());
   DVLOG(1) << "Close";
   CloseAudioUnit();
+  // Notify the audio manager about an upcoming call to ReleaseOutputStream()
+  // and also provide the device ID of the utilized audio device. This is a
+  // trick to ensure that the audio manager only tries to increase the native
+  // I/O buffer size for real audio streams and not for e.g. fake streams.
+  manager_->PrepareForAttemptToIncreaseIOBufferSize(device_);

[o1ka, 2016/05/12 11:30:17]

Ah ok, I see what you mean. Could we simplify it a bit by just having a
dedicated method ReleaseOutputStream(stream, device) in the manager? Than we can
get rid of both device_id_used_by_closing_output_stream_ and
try_to_increase_io_buffer_size_, and make a single call here.

[o1ka, 2016/05/12 12:04:15]

(Actually, it should be named differently, because overloading is not encouraged
by Chromium if I'm not mistaken)

[henrika (OOO until Aug 14), 2016/05/12 13:02:08]

Well, that does not seem that strict but OK I can change it ;-)

[henrika (OOO until Aug 14), 2016/05/12 13:02:08]

Good idea. Done.

   // Inform the audio manager that we have been closed. This will cause our
   // destruction.
   manager_->ReleaseOutputStream(this);
 }
 
 void AUHALStream::Start(AudioSourceCallback* callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DVLOG(1) << "Start";
   DCHECK(callback);
   if (!audio_unit_) {
@@ skipping 33 matching lines @@
   OSSTATUS_DLOG(ERROR, result) << "AudioOutputUnitStart() failed.";
   callback->OnError(this);
 }
 
 void AUHALStream::Stop() {
   DCHECK(thread_checker_.CalledOnValidThread());
   deferred_start_cb_.Cancel();
   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.";
   if (result != noErr)
     source_->OnError(this);
   ReportAndResetStats();
   base::AutoLock auto_lock(source_lock_);
   source_ = NULL;
   stopped_ = true;
 }
@@ skipping 23 matching lines @@
   // If the stream parameters change for any reason, we need to insert a FIFO
   // since the OnMoreData() pipeline can't handle frame size changes.
   if (number_of_frames != number_of_frames_) {
     // Create a FIFO on the fly to handle any discrepancies in callback rates.
     if (!audio_fifo_) {
       // TODO(grunell): We'll only care about the first buffer size change,
       // 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;
       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))));
     }
   }
 
   // Make |output_bus_| wrap the output AudioBufferList.
   WrapBufferList(data, output_bus_.get(), number_of_frames);
 
@@ skipping 313 matching lines @@
   OSStatus result = AudioUnitUninitialize(audio_unit_);
   OSSTATUS_DLOG_IF(ERROR, result != noErr, result)
       << "AudioUnitUninitialize() failed.";
   result = AudioComponentInstanceDispose(audio_unit_);
   OSSTATUS_DLOG_IF(ERROR, result != noErr, result)
       << "AudioComponentInstanceDispose() failed.";
   audio_unit_ = 0;
 }
 
 }  // namespace media