remove unnecessary double allocation

webrtc/sdk/objc/Framework/Classes/avfoundationvideocapturer.mm

 /*
  *  Copyright 2015 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 389 matching lines @@
   _captureSession = captureSession;
   return YES;
 }
 
 - (AVCaptureVideoDataOutput *)videoDataOutput {
   if (!_videoDataOutput) {
     // Make the capturer output NV12. Ideally we want I420 but that's not
     // currently supported on iPhone / iPad.
     AVCaptureVideoDataOutput *videoDataOutput =
         [[AVCaptureVideoDataOutput alloc] init];
-    videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];
     videoDataOutput.videoSettings = @{
       (NSString *)kCVPixelBufferPixelFormatTypeKey :
         @(kCVPixelFormatType_420YpCbCr8BiPlanarFullRange)
     };
     videoDataOutput.alwaysDiscardsLateVideoFrames = NO;
     [videoDataOutput setSampleBufferDelegate:self queue:self.frameQueue];
     _videoDataOutput = videoDataOutput;
   }
   return _videoDataOutput;
 }
@@ skipping 297 matching lines @@
   }
 
   OnFrame(cricket::WebRtcVideoFrame(buffer, webrtc::kVideoRotation_0,
                                     translated_camera_time_us, 0),
           captured_width, captured_height);
 
   CVBufferRelease(image_buffer);
 }
 
 }  // namespace webrtc