Implement mimetype sniffing for extensions.

chrome/browser/download/save_package.cc

 // Copyright (c) 2006-2009 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.
 
 #include "chrome/browser/download/save_package.h"
 
 #include "app/l10n_util.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 239 matching lines @@
   }
 
   file_manager_ = rdh->save_file_manager();
   if (!file_manager_) {
     NOTREACHED();
     return false;
   }
 
   // Create the fake DownloadItem and display the view.
   download_ = new DownloadItem(1, saved_main_file_path_, 0, page_url_, GURL(),
-      FilePath(), Time::Now(), 0, -1, -1, false);
+      "", FilePath(), Time::Now(), 0, -1, -1, false);
   download_->set_manager(tab_contents_->profile()->GetDownloadManager());
   tab_contents_->OnStartDownload(download_);
 
   // Check save type and process the save page job.
   if (save_type_ == SAVE_AS_COMPLETE_HTML) {
     // Get directory
     DCHECK(!saved_main_directory_path_.empty());
     GetAllSavableResourceLinksForCurrentPage();
   } else {
     wait_state_ = NET_FILES;
@@ skipping 922 matching lines @@
                                int index, void* params) {
   SavePackageParam* save_params = reinterpret_cast<SavePackageParam*>(params);
   ContinueSave(save_params, path, index);
   delete save_params;
 }
 
 void SavePackage::FileSelectionCanceled(void* params) {
   SavePackageParam* save_params = reinterpret_cast<SavePackageParam*>(params);
   delete save_params;
 }