Actually free plugin implement vars when running out of process when the

ppapi/proxy/proxy_object_var.h

Index: ppapi/proxy/proxy_object_var.h
===================================================================
--- ppapi/proxy/proxy_object_var.h	(revision 141525)
+++ ppapi/proxy/proxy_object_var.h	(working copy)
@@ -31,6 +31,9 @@
   proxy::PluginDispatcher* dispatcher() const { return dispatcher_; }
   int32 host_var_id() const { return host_var_id_; }
 
+  void* user_data() const { return user_data_; }
+  void set_user_data(void* ud) { user_data_ = ud; }
+
   // Expose AssignVarID on Var so the PluginResourceTracker can call us when
   // it's creating IDs.
   void AssignVarID(int32 id);
@@ -39,6 +42,11 @@
   proxy::PluginDispatcher* dispatcher_;
   int32 host_var_id_;
 
+  // When this object is created as representing a var implemented by the
+  // plugin, this stores the user data so that we can look it up later. See
+  // PluginVarTracker.
+  void* user_data_;
+
   DISALLOW_COPY_AND_ASSIGN(ProxyObjectVar);
 };