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

chrome/browser/chrome_plugin_message_filter.h

Index: chrome/browser/chrome_plugin_message_filter.h
===================================================================
--- chrome/browser/chrome_plugin_message_filter.h	(revision 98657)
+++ chrome/browser/chrome_plugin_message_filter.h	(working copy)
@@ -35,6 +35,10 @@
                                         gfx::NativeWindow caller_window);
 #endif
   void OnGetPluginFinderUrl(std::string* plugin_finder_url);
+  void OnMissingPluginStatus(int status,
+                             int render_process_id,
+                             int render_view_id,
+                             int window);
 
   PluginProcessHost* process_;