Modify the "dangerous download" algorithm as follows. Original patch by Pier...

chrome/browser/download/download_manager.cc

 // 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.
 
 #include "chrome/browser/download/download_manager.h"
 
 #include "app/l10n_util.h"
 #include "app/resource_bundle.h"
 #include "base/callback.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/path_service.h"
 #include "base/rand_util.h"
 #include "base/stl_util-inl.h"
 #include "base/stringprintf.h"
 #include "base/sys_string_conversions.h"
 #include "base/task.h"
 #include "base/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_list.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browser_thread.h"
+#include "chrome/browser/download/download_extensions.h"
 #include "chrome/browser/download/download_file_manager.h"
 #include "chrome/browser/download/download_history.h"
 #include "chrome/browser/download/download_item.h"
 #include "chrome/browser/download/download_prefs.h"
 #include "chrome/browser/download/download_status_updater.h"
 #include "chrome/browser/download/download_util.h"
 #include "chrome/browser/extensions/extensions_service.h"
 #include "chrome/browser/history/download_create_info.h"
 #include "chrome/browser/net/chrome_url_request_context.h"
 #include "chrome/browser/platform_util.h"
@@ skipping 796 matching lines @@
 
 void DownloadManager::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
 bool DownloadManager::ShouldOpenFileBasedOnExtension(
     const FilePath& path) const {
   FilePath::StringType extension = path.Extension();
   if (extension.empty())
     return false;
-  if (download_util::IsExecutableExtension(extension))
+  if (!download_util::IsFileExtensionSafe(extension))
     return false;
   if (Extension::IsExtension(path))
     return false;
   DCHECK(extension[0] == FilePath::kExtensionSeparator);
   extension.erase(0, 1);
   return download_prefs_->IsAutoOpenEnabledForExtension(extension);
 }
 
 bool DownloadManager::IsDownloadProgressKnown() {
   for (DownloadMap::iterator i = in_progress_.begin();
@@ skipping 189 matching lines @@
     observed_download_manager_->RemoveObserver(this);
 }
 
 void DownloadManager::OtherDownloadManagerObserver::ModelChanged() {
   observing_download_manager_->NotifyModelChanged();
 }
 
 void DownloadManager::OtherDownloadManagerObserver::ManagerGoingDown() {
   observed_download_manager_ = NULL;
 }