Enable warning 4389 as an error on windows builds. This will make...

webkit/default_plugin/plugin_database_handler.cc

 // Copyright (c) 2006-2008 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 "webkit/default_plugin/plugin_database_handler.h"
 
 #if defined(USE_SYSTEM_LIBXML)
 #include <parser.h>
 #include <xpath.h>
 #else
@@ skipping 126 matching lines @@
       }
 
       DLOG(INFO) << "Failed to create plugins file "
                  << plugins_file_.c_str() << " Error "
                  << ::GetLastError();
       NOTREACHED();
       return 0;
     }
   }
 
-  unsigned long bytes_written = 0;
+  DWORD bytes_written = 0;
   if (0 == lstrcmpiA(stream->url, plugin_finder_url_.c_str())) {
     DCHECK(plugin_downloads_file_ != INVALID_HANDLE_VALUE);
 
     WriteFile(plugin_downloads_file_, buffer, buffer_length, &bytes_written,
               NULL);
-    DCHECK(buffer_length == bytes_written);
+    DCHECK_EQ(buffer_length, static_cast<int32>(bytes_written));
   }
   return bytes_written;
 }
 
 
 bool PluginDatabaseHandler::ParsePluginList() {
   if (plugin_downloads_file_ == INVALID_HANDLE_VALUE) {
     DLOG(WARNING) << "Invalid plugins file";
     NOTREACHED();
     return false;
@@ skipping 185 matching lines @@
       reinterpret_cast<const char*>(plugin_download_url_val->content);
 
   SplitString(reinterpret_cast<const char*>(plugin_mime_type_vals->content),
               kMimeTypeSeparator, &plugin_detail->mime_types);
 
   plugin_detail->language =
       reinterpret_cast<const char*>(plugin_lang_val->content);
 
   return true;
 }