Make it possible to build without enable_supervised_users.

chrome/browser/ui/webui/browsing_history_handler.h

 // Copyright 2015 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_UI_WEBUI_BROWSING_HISTORY_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_BROWSING_HISTORY_HANDLER_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "base/time/clock.h"
 #include "base/values.h"
 #include "chrome/browser/history/browsing_history_service_handler.h"
 #include "content/public/browser/web_ui_message_handler.h"
 
 namespace history {
 struct QueryOptions;
-}  // namespace history
+}
 
 // The handler for Javascript messages related to the "history" view.
 class BrowsingHistoryHandler :
     public content::WebUIMessageHandler,
     public BrowsingHistoryServiceHandler {
  public:
   BrowsingHistoryHandler();
   ~BrowsingHistoryHandler() override;
 
   // WebUIMessageHandler implementation.
@@ skipping 54 matching lines @@
 
   // The clock used to vend times.
   std::unique_ptr<base::Clock> clock_;
 
   std::unique_ptr<BrowsingHistoryService> browsing_history_service_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowsingHistoryHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_BROWSING_HISTORY_HANDLER_H_