Cleanup some audio classes with C++11 shine!

media/base/audio_converter.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.
 //
 // AudioConverter implementation.  Uses MultiChannelSincResampler for resampling
 // audio, ChannelMixer for channel mixing, and AudioPullFifo for buffering.
 //
 // Delay estimates are provided to InputCallbacks based on the frame delay
 // information reported via the resampler and FIFO units.
 
@@ skipping 179 matching lines @@
   if (audio_fifo_) {
     buffer_delay += base::TimeDelta::FromMicroseconds(
         fifo_frame_delay * input_frame_duration_.InMicroseconds());
   }
 
   // If we only have a single input, avoid an extra copy.
   AudioBus* const provide_input_dest =
       transform_inputs_.size() == 1 ? temp_dest : mixer_input_audio_bus_.get();
 
   // Have each mixer render its data into an output buffer then mix the result.
-  for (InputCallbackSet::iterator it = transform_inputs_.begin();
-       it != transform_inputs_.end(); ++it) {
-    InputCallback* input = *it;
-
+  for (auto* input : transform_inputs_) {
     const float volume = input->ProvideInput(provide_input_dest, buffer_delay);
 
     // Optimize the most common single input, full volume case.
-    if (it == transform_inputs_.begin()) {
+    if (input == transform_inputs_.front()) {
       if (volume == 1.0f) {
         if (temp_dest != provide_input_dest)
           provide_input_dest->CopyTo(temp_dest);
       } else if (volume > 0) {
         for (int i = 0; i < provide_input_dest->channels(); ++i) {
           vector_math::FMUL(
               provide_input_dest->channel(i), volume,
               provide_input_dest->frames(), temp_dest->channel(i));
         }
       } else {
@@ skipping 27 matching lines @@
   else
     SourceCallback(0, dest);
 }
 
 void AudioConverter::CreateUnmixedAudioIfNecessary(int frames) {
   if (!unmixed_audio_ || unmixed_audio_->frames() != frames)
     unmixed_audio_ = AudioBus::Create(input_channel_count_, frames);
 }
 
 }  // namespace media