Assume all providers may give zero suggest responses.

components/omnibox/search_provider.h

Index: components/omnibox/search_provider.h
diff --git a/components/omnibox/search_provider.h b/components/omnibox/search_provider.h
index 13f81dc49868980cf2d92fa382367895f814973d..93a2f0eba3738bc31650e6b19bdff66c4ed7b2ad 100644
--- a/components/omnibox/search_provider.h
+++ b/components/omnibox/search_provider.h
@@ -89,6 +89,7 @@ class SearchProvider : public BaseSearchProvider,
   FRIEND_TEST_ALL_PREFIXES(SearchProviderTest, SessionToken);
   FRIEND_TEST_ALL_PREFIXES(SearchProviderTest, AnswersCache);
   FRIEND_TEST_ALL_PREFIXES(SearchProviderTest, RemoveExtraAnswers);
+  FRIEND_TEST_ALL_PREFIXES(SearchProviderTest, DoesNotProvideOnFocus);
   FRIEND_TEST_ALL_PREFIXES(AutocompleteProviderTest, GetDestinationURL);
   FRIEND_TEST_ALL_PREFIXES(InstantExtendedPrefetchTest, ClearPrefetchedResults);
   FRIEND_TEST_ALL_PREFIXES(InstantExtendedPrefetchTest, SetPrefetchQuery);
@@ -158,7 +159,9 @@ class SearchProvider : public BaseSearchProvider,
   static ACMatches::iterator FindTopMatch(ACMatches* matches);
 
   // AutocompleteProvider:
-  void Start(const AutocompleteInput& input, bool minimal_changes) override;
+  void Start(const AutocompleteInput& input,
+             bool minimal_changes,
+             bool called_due_to_focus) override;
   void Stop(bool clear_cached_results) override;
 
   // BaseSearchProvider: