Revert of Change base::Value::ListStorage to std::vector<base::Value>

components/ntp_snippets/category_rankers/click_based_category_ranker.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 "components/ntp_snippets/category_rankers/click_based_category_ranker.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 
@@ skipping 395 matching lines @@
 
 bool ClickBasedCategoryRanker::ReadOrderFromPrefs(
     std::vector<RankedCategory>* result_categories) const {
   result_categories->clear();
   const base::ListValue* list =
       pref_service_->GetList(prefs::kClickBasedCategoryRankerOrderWithClicks);
   if (!list || list->GetSize() == 0) {
     return false;
   }
 
-  for (const base::Value& value : *list) {
-    const base::DictionaryValue* dictionary;
-    if (!value.GetAsDictionary(&dictionary)) {
+  for (const std::unique_ptr<base::Value>& value : *list) {
+    base::DictionaryValue* dictionary;
+    if (!value->GetAsDictionary(&dictionary)) {
       LOG(DFATAL) << "Failed to parse category data from prefs param "
                   << prefs::kClickBasedCategoryRankerOrderWithClicks
                   << " into dictionary.";
       return false;
     }
     int category_id, clicks;
     if (!dictionary->GetInteger(kCategoryIdKey, &category_id)) {
       LOG(DFATAL) << "Dictionary does not have '" << kCategoryIdKey << "' key.";
       return false;
     }
@@ skipping 90 matching lines @@
                             num_pending_decays * GetTimeBetweenDecays());
 
   if (executed_decays > 0) {
     StoreOrderToPrefs(ordered_categories_);
     return true;
   }
   return false;
 }
 
 }  // namespace ntp_snippets