Win: Don't give some downloads duplicate extensions like .arj.arj...

chrome/browser/views/shell_dialogs_win.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/shell_dialogs.h"
 
 #include <windows.h>
 #include <commdlg.h>
 #include <shlobj.h>
 
@@ skipping 23 matching lines @@
 // SaveAs dialog box and may include the path, |filter_selected| should be
 // '*.something', for example '*.*' or it can be blank (which is treated as
 // *.*). |suggested_ext| should contain the extension without the dot (.) in
 // front, for example 'jpg'.
 std::wstring AppendExtensionIfNeeded(const std::wstring& filename,
                                      const std::wstring& filter_selected,
                                      const std::wstring& suggested_ext) {
   DCHECK(!filename.empty());
   std::wstring return_value = filename;
 
-  // If the user didn't give us a known extension, and we wanted one, add it.
+  // If we wanted a specific extension, but the user's filename deleted it or
+  // changed it to something that the system doesn't understand, re-append.
   std::string selected_mime_type;
+  std::wstring file_extension = file_util::GetFileExtensionFromPath(filename);
   if (!(filter_selected.empty() || filter_selected == L"*.*") &&
       !net::GetMimeTypeFromExtension(
-          file_util::GetFileExtensionFromPath(filename), &selected_mime_type)) {
+          file_extension, &selected_mime_type) &&
+      file_extension != suggested_ext) {
     if (return_value[return_value.length() - 1] != L'.')
       return_value.append(L".");
     return_value.append(suggested_ext);
   }
 
   // Strip any trailing dots, which Windows doesn't allow.
   size_t index = return_value.find_last_not_of(L'.');
   if (index < return_value.size() - 1)
     return_value.resize(index + 1);
 
@@ skipping 1056 matching lines @@
 void SelectFontDialogImpl::FontNotSelected(void* params, RunState run_state) {
   if (listener_)
     listener_->FontSelectionCanceled(params);
   EndRun(run_state);
 }
 
 // static
 SelectFontDialog* SelectFontDialog::Create(Listener* listener) {
   return new SelectFontDialogImpl(listener);
 }