Create ReadingListSuggestionsProvider

components/ntp_snippets/category_rankers/constant_category_ranker.cc

Index: components/ntp_snippets/category_rankers/constant_category_ranker.cc
diff --git a/components/ntp_snippets/category_rankers/constant_category_ranker.cc b/components/ntp_snippets/category_rankers/constant_category_ranker.cc
index 8ba04ab61dbf24518db0d5cd8726816c1edddbeb..ea30b64e15e2641b30769d3f1e14745e2fea819e 100644
--- a/components/ntp_snippets/category_rankers/constant_category_ranker.cc
+++ b/components/ntp_snippets/category_rankers/constant_category_ranker.cc
@@ -73,6 +73,7 @@ ConstantCategoryRanker::GetKnownCategoriesDefaultOrder() {
   switch (choice) {
     case CategoryOrderChoice::GENERAL:
       categories.push_back(KnownCategories::PHYSICAL_WEB_PAGES);
+      categories.push_back(KnownCategories::READING_LIST);
       categories.push_back(KnownCategories::DOWNLOADS);
       categories.push_back(KnownCategories::RECENT_TABS);
       categories.push_back(KnownCategories::FOREIGN_TABS);
@@ -81,6 +82,7 @@ ConstantCategoryRanker::GetKnownCategoriesDefaultOrder() {
       break;
     case CategoryOrderChoice::EMERGING_MARKETS_ORIENTED:
       categories.push_back(KnownCategories::ARTICLES);
+      categories.push_back(KnownCategories::READING_LIST);
       categories.push_back(KnownCategories::DOWNLOADS);
       categories.push_back(KnownCategories::BOOKMARKS);
 
@@ -91,7 +93,7 @@ ConstantCategoryRanker::GetKnownCategoriesDefaultOrder() {
   }
 
   static_assert(
-      static_cast<size_t>(KnownCategories::LOCAL_CATEGORIES_COUNT) == 5,
+      static_cast<size_t>(KnownCategories::LOCAL_CATEGORIES_COUNT) == 6,
       "All local KnownCategories must be present in all orders.");
 
   // Other remote categories will be ordered after these depending on when