Cleanup usage of history namespace in components/history

chrome/browser/jumplist_win.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_JUMPLIST_WIN_H_
 #define CHROME_BROWSER_JUMPLIST_WIN_H_
 
 #include <list>
 #include <string>
 #include <utility>
@@ skipping 15 matching lines @@
 #include "content/public/browser/browser_thread.h"
 
 namespace chrome {
 struct FaviconImageResult;
 }
 
 namespace content {
 class NotificationRegistrar;
 }
 
-class PageUsageData;
 class PrefChangeRegistrar;
 class Profile;
 
 // A class which implements an application JumpList.
 // This class encapsulates operations required for updating an application
 // JumpList:
 // * Retrieving "Most Visited" pages from HistoryService;
 // * Retrieving strings from the application resource;
-// * Creating COM objects used by JumpList from PageUsageData objects;
 // * Adding COM objects to JumpList, etc.
 //
 // This class observes the tabs and policies of the given Profile and updates
 // the JumpList whenever a change is detected.
 //
 // Updating a JumpList requires some file operations and it is not good to
 // update it in a UI thread. To solve this problem, this class posts to a
 // runnable method when it actually updates a JumpList.
 //
 // Note. base::CancelableTaskTracker is not thread safe, so we
@@ skipping 144 matching lines @@
   scoped_ptr<AvatarMenu> avatar_menu_;
 
   // Whether the experiment that is replacing "Most Visited" category with a
   // "People" category is enabled.
   bool use_profiles_category_;
 
   DISALLOW_COPY_AND_ASSIGN(JumpList);
 };
 
 #endif  // CHROME_BROWSER_JUMPLIST_WIN_H_