Use std::unique_ptr for base::DictionaryValue and base::ListValue's internal store.

ios/web/web_state/ui/crw_web_controller.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/web/web_state/ui/crw_web_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #import <objc/runtime.h>
 #include <stddef.h>
@@ skipping 2826 matching lines @@
   if (!message->GetBoolean("unmediated", &unmediated)) {
     DLOG(WARNING) << "JS message parameter not found: unmediated";
     return NO;
   }
   base::ListValue* federations_value = nullptr;
   if (!message->GetList("federations", &federations_value)) {
     DLOG(WARNING) << "JS message parameter not found: federations";
     return NO;
   }
   std::vector<std::string> federations;
-  for (auto federation_value : *federations_value) {
+  for (const auto& federation_value : *federations_value) {
     std::string federation;
     if (!federation_value->GetAsString(&federation)) {
       DLOG(WARNING) << "JS message parameter 'federations' contains wrong type";
       return NO;
     }
     federations.push_back(federation);
   }
   DCHECK(context[web::kUserIsInteractingKey]);
   _webStateImpl->OnCredentialsRequested(
       request_id, net::GURLWithNSURL(context[web::kOriginURLKey]), unmediated,
@@ skipping 2701 matching lines @@
   }
 
   return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
 }
 
 - (NSString*)refererFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:@"Referer"];
 }
 
 @end