More stubbing out. With this and the rest of Linux pending, test_shell links.

webkit/port/bridge/chromium/PluginsChromium.cpp

 // Copyright (c) 2008, Google Inc.
 // All rights reserved.
 // 
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 // 
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 126 matching lines @@
 {
     LoadPlugins(true);
 }
 
 String GetPluginMimeTypeFromExtension(const String& extension) {
     LoadPlugins(false);
 
     std::string mime_type;
     std::string extension_std = WideToUTF8(
         webkit_glue::StringToStdWString(extension));
+#if !defined(__linux__)
+    // TODO(port): unstub once we have plugin support for Linux
     for (size_t i = 0; i < g_plugins.size(); ++i) {
         if (NPAPI::PluginList::SupportsExtension(
                 g_plugins[i], extension_std, &mime_type))
             break;
     }
+#endif
 
     return webkit_glue::StdStringToString(mime_type);
 }
 
 } // namespace WebCore