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

media/audio/mac/audio_manager_mac.cc

Index: media/audio/mac/audio_manager_mac.cc
diff --git a/media/audio/mac/audio_manager_mac.cc b/media/audio/mac/audio_manager_mac.cc
index d88c4b5cefe4eddf183e403d76f43804b3be5026..213ca2cf2f64b09756d797c50eef73a6cc423bc0 100644
--- a/media/audio/mac/audio_manager_mac.cc
+++ b/media/audio/mac/audio_manager_mac.cc
@@ -4,9 +4,7 @@
 
 #include "media/audio/mac/audio_manager_mac.h"
 
-#include <algorithm>
-#include <limits>
-#include <vector>
+#include <stdint.h>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ -483,7 +481,6 @@
 
 AudioParameters AudioManagerMac::GetInputStreamParameters(
     const std::string& device_id) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   AudioDeviceID device = GetAudioDeviceIdByUId(true, device_id);
   if (device == kAudioObjectUnknown) {
     DLOG(ERROR) << "Invalid device " << device_id;
@@ -599,14 +596,12 @@
 
 AudioOutputStream* AudioManagerMac::MakeLinearOutputStream(
     const AudioParameters& params) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   return MakeLowLatencyOutputStream(params, std::string());
 }
 
 AudioOutputStream* AudioManagerMac::MakeLowLatencyOutputStream(
     const AudioParameters& params,
     const std::string& device_id) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   bool device_listener_first_init = false;
   // Lazily create the audio device listener on the first stream creation,
   // even if getting an audio device fails. Otherwise, if we have 0 audio
@@ -675,7 +670,6 @@
 
 AudioInputStream* AudioManagerMac::MakeLinearInputStream(
     const AudioParameters& params, const std::string& device_id) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LINEAR, params.format());
   AudioInputStream* stream = new PCMQueueInAudioInputStream(this, params);
   basic_input_streams_.push_back(stream);
@@ -684,7 +678,6 @@
 
 AudioInputStream* AudioManagerMac::MakeLowLatencyInputStream(
     const AudioParameters& params, const std::string& device_id) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LOW_LATENCY, params.format());
   // Gets the AudioDeviceID that refers to the AudioInputDevice with the device
   // unique id. This AudioDeviceID is used to set the device for Audio Unit.
@@ -701,7 +694,6 @@
 AudioParameters AudioManagerMac::GetPreferredOutputStreamParameters(
     const std::string& output_device_id,
     const AudioParameters& input_params) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   const AudioDeviceID device = GetAudioDeviceIdByUId(false, output_device_id);
   if (device == kAudioObjectUnknown) {
     DLOG(ERROR) << "Invalid output device " << output_device_id;
@@ -863,12 +855,6 @@
   // stream can't handle buffer size larger than its requested buffer size.
   // See http://crbug.com/428706 for a reason why.
 
-  // Update map of actual buffer size given device id if the map is empty.
-  // Stores a base value that most likely be modified as last action in this
-  // method.
-  if (!is_input && output_io_buffer_size_map_.count(device_id) == 0)
-    output_io_buffer_size_map_[device_id] = buffer_size;
-
   if (buffer_size == desired_buffer_size)
     return true;
 
@@ -926,118 +912,15 @@
   // Store the currently used (after a change) I/O buffer frame size.
   *io_buffer_frame_size = buffer_size;
 
-  // If the size was changed, update the actual output buffer size used for the
-  // given device ID.
-  DCHECK(!output_io_buffer_size_map_.empty());
-  if (!is_input && (result == noErr)) {
-    output_io_buffer_size_map_[device_id] = buffer_size;
-  }
-
   return (result == noErr);
 }
 
-bool AudioManagerMac::IncreaseIOBufferSizeIfPossible(AudioDeviceID device_id) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
-  DVLOG(1) << "IncreaseIOBufferSizeIfPossible(id=0x" << std::hex << device_id
-           << ")";
-  // Start by storing the actual I/O buffer size. Then scan all active output
-  // streams using the specified |device_id| and find the minimum requested
-  // buffer size. In addition, store a reference to the audio unit of the first
-  // output stream using |device_id|.
-  DCHECK(!output_io_buffer_size_map_.empty());
-  // All active output streams use the same actual I/O buffer size given
-  // a unique device ID.
-  const size_t& actual_size = output_io_buffer_size_map_[device_id];
-  AudioUnit audio_unit;
-  size_t min_requested_size = std::numeric_limits<std::size_t>::max();
-  for (auto* stream : output_streams_) {
-    if (stream->device_id() == device_id) {
-      if (min_requested_size == std::numeric_limits<std::size_t>::max()) {
-        // Store reference to the first audio unit using the specified ID.
-        audio_unit = stream->audio_unit();
-      }
-      if (stream->requested_buffer_size() < min_requested_size)
-        min_requested_size = stream->requested_buffer_size();
-      DVLOG(1) << "requested:" << stream->requested_buffer_size()
-               << " actual: " << actual_size;
-    }
-  }
-
-  if (min_requested_size == std::numeric_limits<std::size_t>::max()) {
-    DVLOG(1) << "No action since there is no active stream for given device id";
-    return false;
-  }
-
-  // It is only possible to revert to a larger buffer size if the lowest
-  // requested is not in use. Example: if the actual I/O buffer size is 256 and
-  // at least one output stream has asked for 256 as its buffer size, we can't
-  // start using a larger I/O buffer size.
-  DCHECK_GE(min_requested_size, actual_size);
-  if (min_requested_size == actual_size) {
-    DVLOG(1) << "No action since lowest possible size is already in use: "
-             << actual_size;
-    return false;
-  }
-
-  // It should now be safe to increase the I/O buffer size to a new (higher)
-  // value using the |min_requested_size|. Doing so will save system resources.
-  // All active output streams with the same |device_id| are affected by this
-  // change but it is only required to apply the change to one of the streams.
-  DVLOG(1) << "min_requested_size: " << min_requested_size;
-  bool size_was_changed = false;
-  size_t io_buffer_frame_size = 0;
-  bool result =
-      MaybeChangeBufferSize(device_id, audio_unit, 0, min_requested_size,
-                            &size_was_changed, &io_buffer_frame_size);
-  DCHECK_EQ(io_buffer_frame_size, min_requested_size);
-  DCHECK(size_was_changed);
-  return result;
-}
-
-bool AudioManagerMac::AudioDeviceIsUsedForInput(AudioDeviceID device_id) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
-  if (!basic_input_streams_.empty()) {
-    // For Audio Queues and in the default case (Mac OS X), the audio comes
-    // from the system’s default audio input device as set by a user in System
-    // Preferences.
-    AudioDeviceID default_id;
-    GetDefaultDevice(&default_id, true);
-    if (default_id == device_id)
-      return true;
-  }
-
-  // Each low latency streams has its own device ID.
-  for (auto* stream : low_latency_input_streams_) {
-    if (stream->device_id() == device_id)
-      return true;
-  }
-  return false;
-}
-
 void AudioManagerMac::ReleaseOutputStream(AudioOutputStream* stream) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
-  const AudioDeviceID id = static_cast<AUHALStream*>(stream)->device_id();
-  DVLOG(1) << "Closing down output stream with id=0x" << std::hex << id;
-
-  // Start by closing down the specified output stream.
   output_streams_.remove(static_cast<AUHALStream*>(stream));
   AudioManagerBase::ReleaseOutputStream(stream);
-
-  // Prevent attempt to alter buffer size if the released stream was the last
-  // output stream.
-  if (output_streams_.empty())
-    return;
-
-  if (!AudioDeviceIsUsedForInput(id)) {
-    // The current audio device is not used for input. See if it is possible to
-    // increase the IO buffer size (saves power) given the remaining output
-    // audio streams and their buffer size requirements.
-    IncreaseIOBufferSizeIfPossible(id);
-  }
 }
 
 void AudioManagerMac::ReleaseInputStream(AudioInputStream* stream) {
-  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   auto stream_it = std::find(basic_input_streams_.begin(),
                              basic_input_streams_.end(),
                              stream);