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

ios/chrome/browser/ui/history/history_search_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/history/history_search_view_controller.h"
 
-#include "base/ios/weak_nsobject.h"
-#include "base/mac/scoped_nsobject.h"
 #import "ios/chrome/browser/ui/history/history_search_view.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface HistorySearchViewController ()<UITextFieldDelegate> {
-  // Delegate for forwarding interactions with the search view.
-  base::WeakNSProtocol<id<HistorySearchViewControllerDelegate>> _delegate;
   // View displayed by the HistorySearchViewController
-  base::scoped_nsobject<HistorySearchView> _searchView;
+  HistorySearchView* _searchView;
 }
 
 // Action for the cancel button.
 - (void)cancelButtonClicked:(id)sender;
 
 @end
 
 @implementation HistorySearchViewController
-
+@synthesize delegate = _delegate;
 @synthesize enabled = _enabled;
 
 - (void)loadView {
-  _searchView.reset([[HistorySearchView alloc] init]);
+  _searchView = [[HistorySearchView alloc] init];
   [_searchView setSearchBarDelegate:self];
   [_searchView setCancelTarget:self action:@selector(cancelButtonClicked:)];
   self.view = _searchView;
 }
 
 - (void)viewDidAppear:(BOOL)animated {
   [super viewDidAppear:animated];
   [_searchView becomeFirstResponder];
 }
 
-- (void)setDelegate:(id<HistorySearchViewControllerDelegate>)delegate {
-  _delegate.reset(delegate);
-}
-
-- (id<HistorySearchViewControllerDelegate>)delegate {
-  return _delegate;
-}
-
 - (void)setEnabled:(BOOL)enabled {
   _enabled = enabled;
   [_searchView setEnabled:enabled];
 }
 
 - (void)cancelButtonClicked:(id)sender {
   [_searchView clearText];
   [_searchView endEditing:YES];
   [self.delegate historySearchViewControllerDidCancel:self];
 }
@@ skipping 13 matching lines @@
   [self.delegate historySearchViewController:self didRequestSearchForTerm:@""];
   return YES;
 }
 
 - (BOOL)textFieldShouldReturn:(UITextField*)textField {
   [textField resignFirstResponder];
   return YES;
 }
 
 @end