Switch SupportsUserData uses to use unique_ptr.

ios/chrome/browser/web/sad_tab_tab_helper.mm

 // Copyright 2017 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/web/sad_tab_tab_helper.h"
 
 #import <Foundation/Foundation.h>
 
+#include "base/memory/ptr_util.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/chrome/browser/ui/sad_tab/sad_tab_view.h"
 #import "ios/chrome/browser/web/sad_tab_tab_helper_delegate.h"
 #import "ios/web/public/navigation_manager.h"
 #import "ios/web/public/web_state/ui/crw_generic_content_view.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 DEFINE_WEB_STATE_USER_DATA_KEY(SadTabTabHelper);
 
 SadTabTabHelper::SadTabTabHelper(web::WebState* web_state,
                                  id<SadTabTabHelperDelegate> delegate)
     : web::WebStateObserver(web_state), delegate_(delegate) {
   DCHECK(delegate_);
 }
 
 SadTabTabHelper::~SadTabTabHelper() = default;
 
 void SadTabTabHelper::CreateForWebState(web::WebState* web_state,
                                         id<SadTabTabHelperDelegate> delegate) {
   DCHECK(web_state);
   if (!FromWebState(web_state)) {
-    web_state->SetUserData(UserDataKey(),
-                           new SadTabTabHelper(web_state, delegate));
+    web_state->SetUserData(UserDataKey(), base::WrapUnique(new SadTabTabHelper(
+                                              web_state, delegate)));
   }
 }
 
 void SadTabTabHelper::RenderProcessGone() {
   if (!delegate_ || [delegate_ isTabVisibleForTabHelper:this]) {
     PresentSadTab();
   }
 }
 
 void SadTabTabHelper::PresentSadTab() {
   SadTabView* sad_tab_view = [[SadTabView alloc] initWithReloadHandler:^{
     web_state()->GetNavigationManager()->Reload(web::ReloadType::NORMAL, true);
   }];
 
   CRWContentView* content_view =
       [[CRWGenericContentView alloc] initWithView:sad_tab_view];
 
   web_state()->ShowTransientContentView(content_view);
 }