Assume all providers may give zero suggest responses.

chrome/browser/autocomplete/history_quick_provider.h

 // 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.
 
 #ifndef CHROME_BROWSER_AUTOCOMPLETE_HISTORY_QUICK_PROVIDER_H_
 #define CHROME_BROWSER_AUTOCOMPLETE_HISTORY_QUICK_PROVIDER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 13 matching lines @@
 // This class is an autocomplete provider (a pseudo-internal component of
 // the history system) which quickly (and synchronously) provides matching
 // results from recently or frequently visited sites in the profile's
 // history.
 class HistoryQuickProvider : public HistoryProvider {
  public:
   explicit HistoryQuickProvider(Profile* profile);
 
   // AutocompleteProvider. |minimal_changes| is ignored since there is no asynch
   // completion performed.
-  void Start(const AutocompleteInput& input, bool minimal_changes) override;
+  void Start(const AutocompleteInput& input,
+             bool minimal_changes,
+             bool called_due_to_focus) override;
 
   // Disable this provider. For unit testing purposes only. This is required
   // because this provider is closely associated with the HistoryURLProvider
   // and in order to properly test the latter the HistoryQuickProvider must
   // be disabled.
   // TODO(mrossetti): Eliminate this once the HUP has been refactored.
   static void set_disabled(bool disabled) { disabled_ = disabled; }
 
  private:
   friend class HistoryQuickProviderTest;
@@ skipping 25 matching lines @@
   // Only used for testing.
   scoped_ptr<history::InMemoryURLIndex> index_for_testing_;
 
   // This provider is disabled when true.
   static bool disabled_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryQuickProvider);
 };
 
 #endif  // CHROME_BROWSER_AUTOCOMPLETE_HISTORY_QUICK_PROVIDER_H_