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

components/ntp_snippets/category_rankers/click_based_category_ranker.cc

Index: components/ntp_snippets/category_rankers/click_based_category_ranker.cc
diff --git a/components/ntp_snippets/category_rankers/click_based_category_ranker.cc b/components/ntp_snippets/category_rankers/click_based_category_ranker.cc
index 31bf8ae6c60ecee45f9846c57a5afcc106154805..4b4cfa964b72e0f89b06cf7c5d3d5e400e31bf1a 100644
--- a/components/ntp_snippets/category_rankers/click_based_category_ranker.cc
+++ b/components/ntp_snippets/category_rankers/click_based_category_ranker.cc
@@ -413,9 +413,9 @@
     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.";