Assume all providers may give zero suggest responses.

chrome/browser/autocomplete/builtin_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/builtin_provider.h"
 
 #include <algorithm>
 
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 43 matching lines @@
   base::string16 settings(base::ASCIIToUTF16(chrome::kChromeUISettingsHost) +
                           base::ASCIIToUTF16("/"));
   for (size_t i = 0; i < arraysize(kChromeSettingsSubPages); i++) {
     builtins_.push_back(
         settings + base::ASCIIToUTF16(kChromeSettingsSubPages[i]));
   }
 #endif
 }
 
 void BuiltinProvider::Start(const AutocompleteInput& input,
-                            bool minimal_changes) {
+                            bool minimal_changes,
+                            bool on_focus) {
   matches_.clear();
-  if ((input.type() == metrics::OmniboxInputType::INVALID) ||
+  if (on_focus || (input.type() == metrics::OmniboxInputType::INVALID) ||
       (input.type() == metrics::OmniboxInputType::FORCED_QUERY) ||
       (input.type() == metrics::OmniboxInputType::QUERY))
     return;
 
   const size_t kAboutSchemeLength = strlen(url::kAboutScheme);
   const base::string16 kAbout =
       base::ASCIIToUTF16(url::kAboutScheme) +
       base::ASCIIToUTF16(url::kStandardSchemeSeparator);
   const base::string16 kChrome = base::ASCIIToUTF16(content::kChromeUIScheme) +
       base::ASCIIToUTF16(url::kStandardSchemeSeparator);
@@ skipping 83 matching lines @@
                                const ACMatchClassifications& styles) {
   AutocompleteMatch match(this, kRelevance, false,
                           AutocompleteMatchType::NAVSUGGEST);
   match.fill_into_edit = match_string;
   match.inline_autocompletion = inline_completion;
   match.destination_url = GURL(match_string);
   match.contents = match_string;
   match.contents_class = styles;
   matches_.push_back(match);
 }