[iOS] Stop swizzling the |init| method of CameraController.

ios/chrome/browser/ui/qr_scanner/qr_scanner_view_controller.mm

 // Copyright 2016 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.
 
 #import "ios/chrome/browser/ui/qr_scanner/qr_scanner_view_controller.h"
 
 #import <AVFoundation/AVFoundation.h>
 
 #include "base/logging.h"
 #include "base/metrics/user_metrics.h"
@@ skipping 63 matching lines @@
 
 @synthesize delegate = _delegate;
 
 #pragma mark lifecycle
 
 - (instancetype)initWithDelegate:(id<QRScannerViewControllerDelegate>)delegate {
   self = [super initWithNibName:nil bundle:nil];
   if (self) {
     DCHECK(delegate);
     _delegate = delegate;
-    _cameraController = [[CameraController alloc] initWithDelegate:self];
+    _cameraController = [CameraController cameraControllerWithDelegate:self];
   }
   return self;
 }
 
 - (instancetype)initWithNibName:(NSString*)name bundle:(NSBundle*)bundle {
   NOTREACHED();
   return nil;
 }
 
 - (instancetype)initWithCoder:(NSCoder*)coder {
@@ skipping 267 matching lines @@
 - (void)toggleTorch:(id)sender {
   if ([_cameraController isTorchActive]) {
     [self setTorchMode:AVCaptureTorchModeOff];
   } else {
     base::RecordAction(UserMetricsAction("MobileQRScannerTorchOn"));
     [self setTorchMode:AVCaptureTorchModeOn];
   }
 }
 
 @end