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

ios/chrome/browser/ui/webui/history/browsing_history_handler.cc

 // 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.
 
 #include "ios/chrome/browser/ui/webui/history/browsing_history_handler.h"
 
 #include <stddef.h>
 
 #include <set>
 
@@ skipping 438 matching lines @@
       ios::HistoryServiceFactory::GetForBrowserState(
           browser_state, ServiceAccessType::EXPLICIT_ACCESS);
   history::WebHistoryService* web_history =
       ios::WebHistoryServiceFactory::GetForBrowserState(browser_state);
 
   base::Time now = base::Time::Now();
   std::vector<history::ExpireHistoryArgs> expire_list;
   expire_list.reserve(args->GetSize());
 
   DCHECK(urls_to_be_deleted_.empty());
-  for (base::Value* arg : *args) {
+  for (const auto& arg : *args) {
     base::DictionaryValue* deletion = NULL;
     base::string16 url;
     base::ListValue* timestamps = NULL;
 
     // Each argument is a dictionary with properties "url" and "timestamps".
     if (!(arg->GetAsDictionary(&deletion) && deletion->GetString("url", &url) &&
           deletion->GetList("timestamps", &timestamps))) {
       NOTREACHED() << "Unable to extract arguments";
       return;
     }
     DCHECK(timestamps->GetSize() > 0);
 
     // In order to ensure that visits will be deleted from the server and other
     // clients (even if they are offline), create a sync delete directive for
     // each visit to be deleted.
     sync_pb::HistoryDeleteDirectiveSpecifics delete_directive;
     sync_pb::GlobalIdDirective* global_id_directive =
         delete_directive.mutable_global_id_directive();
 
     double timestamp;
     history::ExpireHistoryArgs* expire_args = NULL;
-    for (base::Value* timestamp_value : *timestamps) {
+    for (const auto& timestamp_value : *timestamps) {
       if (!timestamp_value->GetAsDouble(&timestamp)) {
         NOTREACHED() << "Unable to extract visit timestamp.";
         continue;
       }
       base::Time visit_time = base::Time::FromJsTime(timestamp);
       if (!expire_args) {
         GURL gurl(url);
         expire_list.resize(expire_list.size() + 1);
         expire_args = &expire_list.back();
         expire_args->SetTimeRangeForOneDay(visit_time);
@@ skipping 347 matching lines @@
 
 void BrowsingHistoryHandler::OnURLsDeleted(
     history::HistoryService* history_service,
     bool all_history,
     bool expired,
     const history::URLRows& deleted_rows,
     const std::set<GURL>& favicon_urls) {
   if (all_history || DeletionsDiffer(deleted_rows, urls_to_be_deleted_))
     web_ui()->CallJavascriptFunction("historyDeleted");
 }