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

ios/chrome/browser/ui/omnibox/location_bar_view_ios.mm

 // Copyright (c) 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 <UIKit/UIKit.h>
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
@@ skipping 13 matching lines @@
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
 #include "ios/chrome/grit/ios_strings.h"
 #include "ios/chrome/grit/ios_theme_resources.h"
 #import "ios/third_party/material_roboto_font_loader_ios/src/src/MaterialRobotoFontLoader.h"
 #include "ios/web/public/navigation_item.h"
 #include "ios/web/public/navigation_manager.h"
 #include "ios/web/public/ssl_status.h"
 #include "ios/web/public/web_state/web_state.h"
 #include "ui/base/l10n/l10n_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 const CGFloat kClearTextButtonWidth = 28;
 const CGFloat kClearTextButtonHeight = 28;
 
 // Workaround for https://crbug.com/527084 . If there is connection
 // information, always show the icon. Remove this once connection info
 // is available via other UI: https://crbug.com/533581
 bool DoesCurrentPageHaveCertInfo(web::WebState* webState) {
   if (!webState)
     return false;
@@ skipping 255 matching lines @@
 
   CGRect frame = CGRectZero;
   frame.size = CGSizeMake(kClearTextButtonWidth, kClearTextButtonHeight);
   [button setFrame:frame];
 
   clear_button_bridge_.reset(
       [[OmniboxClearButtonBridge alloc] initWithOmniboxView:edit_view_.get()]);
   [button addTarget:clear_button_bridge_
                 action:@selector(clearText)
       forControlEvents:UIControlEventTouchUpInside];
-  clear_text_button_.reset([button retain]);
+  clear_text_button_.reset(button);
 
   SetA11yLabelAndUiAutomationName(clear_text_button_,
                                   IDS_IOS_ACCNAME_CLEAR_TEXT, @"Clear Text");
 }
 
 void LocationBarViewIOS::UpdateRightDecorations() {
   DCHECK(clear_text_button_);
   if (!edit_view_->model()->has_focus()) {
     // Do nothing for iPhone. The right view will be set to nil after the
     // omnibox animation is completed.
     if (IsIPadIdiom())
       [field_ setRightView:nil];
   } else if ([field_ displayedText].empty() &&
              ![field_ isShowingQueryRefinementChip]) {
     [field_ setRightView:nil];
   } else {
     [field_ setRightView:clear_text_button_];
     [clear_text_button_ setAlpha:1];
   }
 }