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

chrome/browser/extensions/crx_installer.h

 // Copyright (c) 2009 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_CRX_INSTALLER_H_
 #define CHROME_BROWSER_EXTENSIONS_CRX_INSTALLER_H_
 
 #include <string>
 
 #include "base/file_path.h"
 #include "base/ref_counted.h"
-#include "base/task.h"
 #include "chrome/browser/extensions/extension_install_ui.h"
 #include "chrome/browser/extensions/extensions_service.h"
 #include "chrome/browser/extensions/sandboxed_extension_unpacker.h"
 #include "chrome/common/extensions/extension.h"
 
 class SkBitmap;
 
 // This class installs a crx file into a profile.
 //
 // Installing a CRX is a multi-step process, including unpacking the crx,
@@ skipping 181 matching lines @@
   bool apps_require_extension_mime_type_;
 
   // The value of the content type header sent with the CRX.
   // Ignorred unless |require_extension_mime_type_| is true.
   std::string original_mime_type_;
 
   DISALLOW_COPY_AND_ASSIGN(CrxInstaller);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_CRX_INSTALLER_H_