[Hotword] Ok Google options disappear if search provider is changed from

chrome/browser/search/hotword_service.h

 // Copyright 2013 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_SEARCH_HOTWORD_SERVICE_H_
 #define CHROME_BROWSER_SEARCH_HOTWORD_SERVICE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 130 matching lines @@
 
   // Return true if this profile corresponds to the currently active user.
   bool UserIsActive();
 
   // Returns a pointer to the audio history handler.
   HotwordAudioHistoryHandler* GetAudioHistoryHandler();
 
   // Sets the audio history handler. Used for tests.
   void SetAudioHistoryHandler(HotwordAudioHistoryHandler* handler);
 
+  // Turn off the currently enabled version of hotwording if one exists.
+  void DisableHotwordPreferences();
+
  private:
   class HotwordUserSessionStateObserver;
 
   // Callback for webstore extension installer.
   void InstalledFromWebstoreCallback(
       int num_tries,
       bool success,
       const std::string& error,
       extensions::webstore_install::Result result);
 
@@ skipping 30 matching lines @@
 
   // The WeakPtrFactory should be the last member, so the weak pointer
   // gets invalidated before the destructors for other members run,
   // to avoid callbacks into a half-destroyed object.
   base::WeakPtrFactory<HotwordService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HotwordService);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_HOTWORD_SERVICE_H_