Eliminate implicit conversion from scoped_refptr<T> to T*

webkit/plugins/ppapi/host_globals.cc

 // 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.
 
 #include "webkit/plugins/ppapi/host_globals.h"
 
 #include <limits>
 
 #include "base/logging.h"
 #include "base/rand_util.h"
@@ skipping 45 matching lines @@
 }
 
 ::ppapi::ResourceTracker* HostGlobals::GetResourceTracker() {
   return &resource_tracker_;
 }
 
 ::ppapi::VarTracker* HostGlobals::GetVarTracker() {
   return &host_var_tracker_;
 }
 
-::ppapi::CallbackTracker* HostGlobals::GetCallbackTrackerForInstance(
-    PP_Instance instance) {
+scoped_refptr< ::ppapi::CallbackTracker>
+HostGlobals::GetCallbackTrackerForInstance(PP_Instance instance) {
   std::map<PP_Instance, linked_ptr<InstanceData> >::iterator found =
       instance_map_.find(instance);
   if (found == instance_map_.end())
-    return NULL;
+    return scoped_refptr< ::ppapi::CallbackTracker>;
 
   return found->second->instance->module()->GetCallbackTracker();
 }
 
 ::ppapi::FunctionGroupBase* HostGlobals::GetFunctionAPI(PP_Instance pp_instance,
                                                         ::ppapi::ApiID id) {
   // Get the instance object. This also ensures that the instance data is in
   // the map, since we need it below.
   PluginInstance* instance = GetInstance(pp_instance);
   if (!instance)
@@ skipping 124 matching lines @@
     return NULL;
   return found->second->instance;
 }
 
 bool HostGlobals::IsHostGlobals() const {
   return true;
 }
 
 }  // namespace ppapi
 }  // namespace webkit