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

webkit/plugins/ppapi/host_var_tracker.h

 // Copyright (c) 2012 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.
 
 #ifndef WEBKIT_PLUGINS_PPAPI_HOST_VAR_TRACKER_H_
 #define WEBKIT_PLUGINS_PPAPI_HOST_VAR_TRACKER_H_
 
 #include <map>
 
 #include "base/basictypes.h"
@@ skipping 38 matching lines @@
   // instance. Returns NULL if there is no NPObjectVar corresponding to the
   // given NPObject for the given instance. See AddNPObjectVar above.
   ::ppapi::NPObjectVar* NPObjectVarForNPObject(PP_Instance instance,
                                                NPObject* np_object);
 
   // Returns the number of NPObjectVar's associated with the given instance.
   // Returns 0 if the instance isn't known.
   WEBKIT_PLUGINS_EXPORT int GetLiveNPObjectVarsForInstance(
       PP_Instance instance) const;
 
-  // Forcibly deletes all np object vars for the given instance. Used for
-  // instance cleanup.
-  void ForceFreeNPObjectsForInstance(PP_Instance instance);
+  // VarTracker public implementation.
+  virtual void DidDeleteInstance(PP_Instance instance) OVERRIDE;
 
  private:
-  // VarTracker implementation.
+  // VarTracker private implementation.
   virtual ::ppapi::ArrayBufferVar* CreateArrayBuffer(
       uint32 size_in_bytes) OVERRIDE;
 
   // Clear the reference count of the given object and remove it from
   // live_vars_.
   void ForceReleaseNPObject(const base::WeakPtr< ::ppapi::NPObjectVar>& object);
 
   typedef std::map<NPObject*, base::WeakPtr< ::ppapi::NPObjectVar> >
       NPObjectToNPObjectVarMap;
 
   // Lists all known NPObjects, first indexed by the corresponding instance,
   // then by the NPObject*. This allows us to look up an NPObjectVar given
   // these two pieces of information.
   //
   // The instance map is lazily managed, so we'll add the
   // NPObjectToNPObjectVarMap lazily when the first NPObject var is created,
   // and delete it when it's empty.
   typedef std::map<PP_Instance, linked_ptr<NPObjectToNPObjectVarMap> >
       InstanceMap;
   InstanceMap instance_map_;
 
   DISALLOW_COPY_AND_ASSIGN(HostVarTracker);
 };
 
 }  // namespace ppapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_PPAPI_HOST_VAR_TRACKER_H_