[NTP::SectionOrder] Preserve added categories on ClearHistory.

components/ntp_snippets/content_suggestions_service.cc

Index: components/ntp_snippets/content_suggestions_service.cc
diff --git a/components/ntp_snippets/content_suggestions_service.cc b/components/ntp_snippets/content_suggestions_service.cc
index 6469882b963e3b90cad774a0cb7932b5247179d4..712589a8297f9c49e14420bfd00713d07fc46b91 100644
--- a/components/ntp_snippets/content_suggestions_service.cc
+++ b/components/ntp_snippets/content_suggestions_service.cc
@@ -130,6 +130,7 @@ void ContentSuggestionsService::ClearHistory(
   for (const auto& provider : providers_) {
     provider->ClearHistory(begin, end, filter);
   }
+  category_ranker_->ClearHistory(begin, end);
 }
 
 void ContentSuggestionsService::ClearAllCachedSuggestions() {