Assume all providers may give zero suggest responses.

chrome/browser/autocomplete/zero_suggest_provider.cc

Index: chrome/browser/autocomplete/zero_suggest_provider.cc
diff --git a/chrome/browser/autocomplete/zero_suggest_provider.cc b/chrome/browser/autocomplete/zero_suggest_provider.cc
index 436f7b61666d12d0290a26f0fa222af76c52b57f..3feaae3fbcf6257b60ad7a09518d12f5fb2e472d 100644
--- a/chrome/browser/autocomplete/zero_suggest_provider.cc
+++ b/chrome/browser/autocomplete/zero_suggest_provider.cc
@@ -91,9 +91,11 @@ void ZeroSuggestProvider::RegisterProfilePrefs(
 }
 
 void ZeroSuggestProvider::Start(const AutocompleteInput& input,
-                                bool minimal_changes) {
+                                bool minimal_changes,
+                                bool called_due_to_focus) {
   matches_.clear();
-  if (input.type() == metrics::OmniboxInputType::INVALID)
+  if (!called_due_to_focus ||
+      input.type() == metrics::OmniboxInputType::INVALID)
     return;
 
   Stop(true);
@@ -177,10 +179,6 @@ void ZeroSuggestProvider::AddProviderInfo(ProvidersInfo* provider_info) const {
     provider_info->back().set_times_returned_results_in_session(1);
 }
 
-bool ZeroSuggestProvider::ProvidesMatchesOnOmniboxFocus() const {
-  return true;
-}
-
 void ZeroSuggestProvider::ResetSession() {
   // The user has started editing in the omnibox, so leave
   // |field_trial_triggered_in_session_| unchanged and set