Assume all providers may give zero suggest responses.

components/omnibox/keyword_provider.cc

 // Copyright 2014 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 "components/omnibox/keyword_provider.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/strings/string16.h"
@@ skipping 181 matching lines @@
     const base::string16& text,
     const base::string16& keyword,
     const AutocompleteInput& input) {
   // A verbatim match is allowed to be the default match.
   return CreateAutocompleteMatch(
       GetTemplateURLService()->GetTemplateURLForKeyword(keyword), input,
       keyword.length(), SplitReplacementStringFromInput(text, true), true, 0);
 }
 
 void KeywordProvider::Start(const AutocompleteInput& input,
-                            bool minimal_changes) {
+                            bool minimal_changes,
+                            bool called_due_to_focus) {
   // This object ensures we end keyword mode if we exit the function without
   // toggling keyword mode to on.
   ScopedEndExtensionKeywordMode keyword_mode_toggle(extensions_delegate_.get());
 
   matches_.clear();
 
   if (!minimal_changes) {
     done_ = true;
 
     // Input has changed. Increment the input ID so that we can discard any
     // stale extension suggestions that may be incoming.
     if (extensions_delegate_)
       extensions_delegate_->IncrementInputId();
   }
 
+  if (called_due_to_focus)
+    return;
+
   // Split user input into a keyword and some query input.
   //
   // We want to suggest keywords even when users have started typing URLs, on
   // the assumption that they might not realize they no longer need to go to a
   // site to be able to search it.  So we call CleanUserInputKeyword() to strip
   // any initial scheme and/or "www.".  NOTE: Any heuristics or UI used to
   // automatically/manually create keywords will need to be in sync with
   // whatever we do here!
   //
   // TODO(pkasting): http://crbug/347744 If someday we remember usage frequency
@@ skipping 234 matching lines @@
         ACMatchClassification::NONE, &match->contents_class);
   }
 }
 
 TemplateURLService* KeywordProvider::GetTemplateURLService() const {
   // Make sure the model is loaded. This is cheap and quickly bails out if
   // the model is already loaded.
   model_->Load();
   return model_;
 }