Moved the following IPC messages used by the chrome NPAPI plugin installer out of content

webkit/plugins/npapi/webplugin_delegate_impl_win.cc

Index: webkit/plugins/npapi/webplugin_delegate_impl_win.cc
===================================================================
--- webkit/plugins/npapi/webplugin_delegate_impl_win.cc	(revision 98657)
+++ webkit/plugins/npapi/webplugin_delegate_impl_win.cc	(working copy)
@@ -532,14 +532,6 @@
   }
 }
 
-void WebPluginDelegateImpl::InstallMissingPlugin() {
-  NPEvent evt;
-  evt.event = default_plugin::kInstallMissingPluginMessage;
-  evt.lParam = 0;
-  evt.wParam = 0;
-  instance()->NPP_HandleEvent(&evt);
-}
-
 bool WebPluginDelegateImpl::WindowedCreatePlugin() {
   DCHECK(!windowed_handle_);