ObjC: Fix quality scaling for injected encoders

webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCVideoCodec.mm

 /*
  *  Copyright 2017 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 36 matching lines @@
   cricket::VideoCodec codec([NSString stdStringForString:_name]);
   for (NSString *paramKey in _parameters.allKeys) {
     codec.SetParam([NSString stdStringForString:paramKey],
                    [NSString stdStringForString:_parameters[paramKey]]);
   }
 
   return codec;
 }
 
 @end
+
+@implementation RTCVideoEncoderQpThresholds
+
+@synthesize low = _low;
+@synthesize high = _high;
+
+- (instancetype)initWithThresholdsLow:(NSInteger)low high:(NSInteger)high {
+  if (self = [super init]) {
+    _low = low;
+    _high = high;
+  }
+  return self;
+}
+
+@end