[ObjC ARC] Converts ios/chrome/browser/ui/elements:elements to ARC.

ios/chrome/browser/ui/elements/selector_picker_presentation_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/elements/selector_picker_presentation_controller.h"
 
-#import "base/mac/objc_property_releaser.h"
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
 
-@interface SelectorPickerPresentationController () {
-  base::mac::ObjCPropertyReleaser
-      _propertyReleaser_SelectorPickerPresentationController;
-}
-@property(nonatomic, retain) UIView* dimmingView;
+@interface SelectorPickerPresentationController ()
+@property(nonatomic, strong) UIView* dimmingView;
 @end
 
 @implementation SelectorPickerPresentationController
 
 @synthesize dimmingView = _dimmingView;
 
 - (instancetype)initWithPresentedViewController:(UIViewController*)presented
                        presentingViewController:(UIViewController*)presenting {
   self = [super initWithPresentedViewController:presented
                        presentingViewController:presenting];
   if (self) {
-    _propertyReleaser_SelectorPickerPresentationController.Init(
-        self, [SelectorPickerPresentationController class]);
     _dimmingView = [[UIView alloc] initWithFrame:CGRectZero];
     _dimmingView.backgroundColor = [UIColor colorWithWhite:0 alpha:0.4];
   }
   return self;
 }
 
 - (CGRect)frameOfPresentedViewInContainerView {
   CGSize containerSize = self.containerView.frame.size;
   CGSize pickerSize = [self.presentedView
       systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
   return CGRectMake(0, containerSize.height - pickerSize.height,
                     containerSize.width, pickerSize.height);
 }
 
 - (void)containerViewWillLayoutSubviews {
   self.dimmingView.frame = self.containerView.bounds;
   self.presentedView.frame = [self frameOfPresentedViewInContainerView];
 }
 
 - (void)presentationTransitionWillBegin {
   [self.containerView addSubview:self.dimmingView];
 }
 
 - (void)dismissalTransitionDidEnd:(BOOL)completed {
   [self.dimmingView removeFromSuperview];
 }
 
 @end