Use the new callback tracker and delete the old one

ppapi/shared_impl/resource_tracker.h

 // Copyright (c) 2011 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 PPAPI_SHARED_IMPL_RESOURCE_TRACKER_H_
 #define PPAPI_SHARED_IMPL_RESOURCE_TRACKER_H_
 
 #include <set>
 
 #include "base/basictypes.h"
@@ skipping 41 matching lines @@
   // resource will have 0 plugin refcount. This is called by the resource
   // constructor.
   //
   // Returns 0 if the resource could not be added.
   virtual PP_Resource AddResource(Resource* object);
 
   // The opposite of AddResource, this removes the tracking information for
   // the given resource. It's called from the resource destructor.
   virtual void RemoveResource(Resource* object);
 
-  // Calls LastPluginRefWasDeleted on the given resource object. This is
-  // provided because the derived class in webkit/plugins/ppapi needs to
-  // perform additional operations at this time.
-  virtual void LastPluginRefWasDeleted(Resource* object);
+  // Calls LastPluginRefWasDeleted on the given resource object and cancels
+  // pending callbacks for the resource.
+  void LastPluginRefWasDeleted(Resource* object);
 
  private:
   typedef std::set<PP_Resource> ResourceSet;
 
   struct InstanceData {
     // Lists all resources associated with the given instance as non-owning
     // pointers. This allows us to notify those resources that the instance is
     // going away (otherwise, they may crash if they outlive the instance).
     ResourceSet resources;
   };
@@ skipping 14 matching lines @@
   ResourceMap live_resources_;
 
   int32 last_resource_value_;
 
   DISALLOW_COPY_AND_ASSIGN(ResourceTracker);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_RESOURCE_TRACKER_H_