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

ios/chrome/browser/ui/stack_view/stack_card.mm

 // Copyright 2012 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/stack_view/stack_card.h"
 
 #include "base/logging.h"
-#import "base/mac/scoped_nsobject.h"
 #import "ios/chrome/browser/ui/rtl_geometry.h"
 #import "ios/chrome/browser/ui/stack_view/card_view.h"
 #import "ios/chrome/browser/ui/ui_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface StackCard () {
-  id<StackCardViewProvider> _viewProvider;
-  base::scoped_nsobject<CardView> _view;
+  __weak id<StackCardViewProvider> _viewProvider;
+  CardView* _view;
 }
 
 // The pixel-aligned frame generated by applying |self.layout| under the current
 // language direction.
 @property(nonatomic, readonly) CGRect frame;
 
 // Applies |self.layout| to the underlying CardView if it exists.
 - (void)applyLayout;
 
 @end
@@ skipping 14 matching lines @@
   return self;
 }
 
 - (instancetype)init {
   NOTREACHED();
   return nil;
 }
 
 - (void)releaseView {
   if (self.viewIsLive)
-    _view.reset();
+    _view = nil;
 }
 
 #pragma mark - Properties
 
 - (CardView*)view {
   if (!_view) {
-    _view.reset([[_viewProvider cardViewWithFrame:self.frame forStackCard:self]
-        retain]);
-    _view.get().isActiveTab = _isActiveTab;
+    _view = [_viewProvider cardViewWithFrame:self.frame forStackCard:self];
+    _view.isActiveTab = _isActiveTab;
   }
-  return _view.get();
+  return _view;
 }
 
 - (void)setLayout:(LayoutRect)layout {
   if (!LayoutRectEqualToRect(_layout, layout)) {
     _layout = layout;
     [self applyLayout];
   }
 }
 
 - (CGSize)size {
@@ skipping 12 matching lines @@
 
 - (void)setSynchronizeView:(BOOL)synchronizeView {
   if (_synchronizeView != synchronizeView) {
     _synchronizeView = synchronizeView;
     [self applyLayout];
   }
 }
 
 - (void)setIsActiveTab:(BOOL)isActiveTab {
   _isActiveTab = isActiveTab;
-  _view.get().isActiveTab = _isActiveTab;
+  _view.isActiveTab = _isActiveTab;
 }
 
 - (BOOL)viewIsLive {
   return _view != nil;
 }
 
 - (CGRect)frame {
   return AlignRectOriginAndSizeToPixels(LayoutRectGetRect(self.layout));
 }
 
 #pragma mark -
 
 - (void)applyLayout {
   if (!self.viewIsLive || !self.synchronizeView)
     return;
   self.view.frame = self.frame;
 }
 
 @end