Assume all providers may give zero suggest responses.

components/omnibox/keyword_provider.h

Index: components/omnibox/keyword_provider.h
diff --git a/components/omnibox/keyword_provider.h b/components/omnibox/keyword_provider.h
index f0dfed2fb07c99e040cd31fb52763daa1ce35d63..a54612109d4cd314f129a62857db30cbfd41019c 100644
--- a/components/omnibox/keyword_provider.h
+++ b/components/omnibox/keyword_provider.h
@@ -94,7 +94,9 @@ class KeywordProvider : public AutocompleteProvider {
                                         const AutocompleteInput& input);
 
   // AutocompleteProvider:
-  void Start(const AutocompleteInput& input, bool minimal_changes) override;
+  void Start(const AutocompleteInput& input,
+             bool minimal_changes,
+             bool on_focus) override;
   void Stop(bool clear_cached_results) override;
 
  private: