Convert ios_web_shell to ARC.

ios/web/shell/view_controller.mm

 // Copyright 2014 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/web/shell/view_controller.h"
 
 #import <MobileCoreServices/MobileCoreServices.h>
 
 #include <stdint.h>
 
 #include <memory>
 #include <utility>
 
-#include "base/mac/objc_property_releaser.h"
 #import "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 #include "ios/net/cookies/cookie_store_ios.h"
 #import "ios/net/crn_http_protocol_handler.h"
 #import "ios/net/empty_nsurlcache.h"
 #import "ios/net/request_tracker.h"
 #import "ios/web/public/navigation_manager.h"
 #include "ios/web/public/referrer.h"
 #import "ios/web/public/web_state/context_menu_params.h"
 #include "ios/web/public/web_state/web_state.h"
 #import "ios/web/public/web_state/web_state_delegate_bridge.h"
 #import "ios/web/public/web_state/web_state_observer_bridge.h"
 #import "net/base/mac/url_conversions.h"
 #include "ui/base/page_transition_types.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 NSString* const kWebShellBackButtonAccessibilityLabel = @"Back";
 NSString* const kWebShellForwardButtonAccessibilityLabel = @"Forward";
 NSString* const kWebShellAddressFieldAccessibilityLabel = @"Address field";
 
 using web::NavigationManager;
 
 @interface ViewController ()<CRWWebStateDelegate,
                              CRWWebStateObserver,
                              UITextFieldDelegate> {
   web::BrowserState* _browserState;
   std::unique_ptr<web::WebState> _webState;
   std::unique_ptr<web::WebStateObserverBridge> _webStateObserver;
   std::unique_ptr<web::WebStateDelegateBridge> _webStateDelegate;
-
-  base::mac::ObjCPropertyReleaser _propertyReleaser_ViewController;
 }
 @property(nonatomic, assign, readonly) NavigationManager* navigationManager;
-@property(nonatomic, readwrite, retain) UITextField* field;
+@property(nonatomic, readwrite, strong) UITextField* field;
 @end
 
 @implementation ViewController
 
 @synthesize field = _field;
 @synthesize containerView = _containerView;
 @synthesize toolbarView = _toolbarView;
 
 - (instancetype)initWithBrowserState:(web::BrowserState*)browserState {
   self = [super initWithNibName:@"MainView" bundle:nil];
   if (self) {
-    _propertyReleaser_ViewController.Init(self, [ViewController class]);
     _browserState = browserState;
   }
   return self;
 }
 
 - (void)dealloc {
   net::HTTPProtocolHandlerDelegate::SetInstance(nullptr);
   net::RequestTracker::SetRequestTrackerFactory(nullptr);
-  [super dealloc];
 }
 
 - (void)viewDidLoad {
   [super viewDidLoad];
 
   // Set up the toolbar buttons.
   UIButton* back = [UIButton buttonWithType:UIButtonTypeCustom];
   [back setImage:[UIImage imageNamed:@"toolbar_back"]
         forState:UIControlStateNormal];
   [back setFrame:CGRectMake(0, 0, 44, 44)];
@@ skipping 220 matching lines @@
   [alert addAction:[UIAlertAction actionWithTitle:@"Cancel"
                                             style:UIAlertActionStyleCancel
                                           handler:nil]];
 
   [self presentViewController:alert animated:YES completion:nil];
 
   return YES;
 }
 
 @end