Always include base extension type in Mac select file dialog

ui/base/dialogs/select_file_dialog_mac.mm

 // 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.
 
 #include "ui/base/dialogs/select_file_dialog.h"
 
 #import <Cocoa/Cocoa.h>
 #include <CoreServices/CoreServices.h>
 
 #include <map>
@@ skipping 209 matching lines @@
       // will be part of one list. To be safe, allow the types of all the
       // specified extensions.
       NSMutableSet* file_type_set = [NSMutableSet set];
       for (size_t i = 0; i < file_types->extensions.size(); ++i) {
         const std::vector<FilePath::StringType>& ext_list =
             file_types->extensions[i];
         for (size_t j = 0; j < ext_list.size(); ++j) {
           base::mac::ScopedCFTypeRef<CFStringRef> uti(
               CreateUTIFromExtension(ext_list[j]));
           [file_type_set addObject:base::mac::CFToNSCast(uti.get())];
+
+          // Always allow the extension itself, in case the UTI doesn't map
+          // back to the original extension correctly. This occurs with dynamic
+          // UTIs on 10.7 and 10.8.
+          // See http://crbug.com/148840, http://openradar.me/12316273
+          base::mac::ScopedCFTypeRef<CFStringRef> ext_cf(
+              base::SysUTF8ToCFStringRef(ext_list[j]));
+          [file_type_set addObject:base::mac::CFToNSCast(ext_cf.get())];
         }
       }
       allowed_file_types = [file_type_set allObjects];
     }
     if (type == SELECT_SAVEAS_FILE)
       [dialog setAllowedFileTypes:allowed_file_types];
     // else we'll pass it in when we run the open panel
 
     if (file_types->include_all_files || file_types->extensions.empty())
       [dialog setAllowsOtherFileTypes:YES];
@@ skipping 167 matching lines @@
 
 namespace ui {
 
 SelectFileDialog* CreateMacSelectFileDialog(
     SelectFileDialog::Listener* listener,
     SelectFilePolicy* policy) {
   return new SelectFileDialogImpl(listener, policy);
 }
 
 }  // namespace ui