Provide description_class in search provider.

components/omnibox/base_search_provider.cc

Index: components/omnibox/base_search_provider.cc
diff --git a/components/omnibox/base_search_provider.cc b/components/omnibox/base_search_provider.cc
index a18b66c2e26c79041a53e8865af383cdfdb94f4d..bfedaf4ce7d6ce9ef12175e897d230774995149a 100644
--- a/components/omnibox/base_search_provider.cc
+++ b/components/omnibox/base_search_provider.cc
@@ -222,8 +222,11 @@ AutocompleteMatch BaseSearchProvider::CreateSearchSuggestion(
             suggestion.suggestion().length() - match.contents.length()));
   }
 
-  if (!suggestion.annotation().empty())
+  if (!suggestion.annotation().empty()) {
     match.description = suggestion.annotation();
+    AutocompleteMatch::AddLastClassificationIfNecessary(
+        &match.description_class, 0, ACMatchClassification::NONE);
+  }
 
   // suggestion.match_contents() should have already been collapsed.
   match.allowed_to_be_default_match =