Adds output audio volume to iOS logs

webrtc/modules/audio_device/ios/objc/RTCAudioSession.mm

 /*
  *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 83 matching lines @@
        "  category: %@\n"
        "  categoryOptions: %ld\n"
        "  mode: %@\n"
        "  isActive: %d\n"
        "  sampleRate: %.2f\n"
        "  IOBufferDuration: %f\n"
        "  outputNumberOfChannels: %ld\n"
        "  inputNumberOfChannels: %ld\n"
        "  outputLatency: %f\n"
        "  inputLatency: %f\n"
+       "  outputVolume: %f\n"
        "}";
   NSString *description = [NSString stringWithFormat:format,
       self.category, (long)self.categoryOptions, self.mode,
       self.isActive, self.sampleRate, self.IOBufferDuration,
       self.outputNumberOfChannels, self.inputNumberOfChannels,
-      self.outputLatency, self.inputLatency];
+      self.outputLatency, self.inputLatency, self.outputVolume];
   return description;
 }
 
 - (void)setIsActive:(BOOL)isActive {
   @synchronized(self) {
     _isActive = isActive;
   }
 }
 
 - (BOOL)isActive {
@@ skipping 702 matching lines @@
 - (void)notifyDidStopPlayOrRecord {
   for (auto delegate : self.delegates) {
     SEL sel = @selector(audioSessionDidStopPlayOrRecord:);
     if ([delegate respondsToSelector:sel]) {
       [delegate audioSessionDidStopPlayOrRecord:self];
     }
   }
 }
 
 @end