Assume all providers may give zero suggest responses.

chrome/browser/autocomplete/zero_suggest_provider.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/autocomplete/zero_suggest_provider.h"
 
 #include "base/callback.h"
 #include "base/i18n/case_conversion.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/metrics/histogram.h"
@@ skipping 73 matching lines @@
 // static
 void ZeroSuggestProvider::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterStringPref(
       prefs::kZeroSuggestCachedResults,
       std::string(),
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
 }
 
 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);
   field_trial_triggered_ = false;
   field_trial_triggered_in_session_ = false;
   results_from_cache_ = false;
   permanent_text_ = input.text();
   current_query_ = input.current_url().spec();
   current_page_classification_ = input.current_page_classification();
   current_url_match_ = MatchForCurrentURL();
@@ skipping 63 matching lines @@
   }
   BaseSearchProvider::DeleteMatch(match);
 }
 
 void ZeroSuggestProvider::AddProviderInfo(ProvidersInfo* provider_info) const {
   BaseSearchProvider::AddProviderInfo(provider_info);
   if (!results_.suggest_results.empty() || !results_.navigation_results.empty())
     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
   // |field_trial_triggered_| to false since zero suggest is inactive now.
   field_trial_triggered_ = false;
 }
 
 ZeroSuggestProvider::ZeroSuggestProvider(
   AutocompleteProviderListener* listener,
   TemplateURLService* template_url_service,
@@ skipping 288 matching lines @@
   if (!json_data.empty()) {
     scoped_ptr<base::Value> data(
         SearchSuggestionParser::DeserializeJsonData(json_data));
     if (data && ParseSuggestResults(
             *data, kDefaultZeroSuggestRelevance, false, &results_)) {
       ConvertResultsToAutocompleteMatches();
       results_from_cache_ = !matches_.empty();
     }
   }
 }