Refactor MHTMLGenerator to allow getting sending the data to a file descriptor.

content/browser/download/save_package.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 CONTENT_BROWSER_DOWNLOAD_SAVE_PACKAGE_H_
 #define CONTENT_BROWSER_DOWNLOAD_SAVE_PACKAGE_H_
 
 #include <queue>
 #include <set>
 #include <string>
@@ skipping 111 matching lines @@
   void GetSaveInfo();
 
  private:
   friend class base::RefCountedThreadSafe<SavePackage>;
 
   void InitWithDownloadItem(
       const SavePackageDownloadCreatedCallback& download_created_callback,
       DownloadItemImpl* item);
 
   // Callback for WebContents::GenerateMHTML().
-  void OnMHTMLGenerated(const base::FilePath& path, int64 size);
+  void OnMHTMLGenerated(int64 size);
 
   // For testing only.
   SavePackage(WebContents* web_contents,
               const base::FilePath& file_full_path,
               const base::FilePath& directory_full_path);
 
   virtual ~SavePackage();
 
   // Notes from Init() above applies here as well.
   void InternalInit();
@@ skipping 188 matching lines @@
   friend class SavePackageTest;
   FRIEND_TEST_ALL_PREFIXES(SavePackageTest, TestSuggestedSaveNames);
   FRIEND_TEST_ALL_PREFIXES(SavePackageTest, TestLongSafePureFilename);
 
   DISALLOW_COPY_AND_ASSIGN(SavePackage);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_SAVE_PACKAGE_H_