Attempt four at landing the "histogram.h removed from message_loop.h" patch.

chrome/browser/extensions/extension_prefs.h

 // Copyright (c) 2010 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_EXTENSIONS_EXTENSION_PREFS_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/linked_ptr.h"
-#include "base/task.h"
 #include "base/time.h"
 #include "chrome/browser/pref_service.h"
 #include "chrome/common/extensions/extension.h"
 #include "googleurl/src/gurl.h"
 
 // Class for managing global and per-extension preferences.
 // This class is instantiated by ExtensionsService, so it should be accessed
 // from there.
 class ExtensionPrefs {
  public:
@@ skipping 177 matching lines @@
   // Base extensions install directory.
   FilePath install_directory_;
 
   // The URLs of all of the toolstrips.
   URLList shelf_order_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionPrefs);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_