Create a thread-safe observer list. Will be used

base/task.h

 // Copyright (c) 2006-2008 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 BASE_TASK_H__
 #define BASE_TASK_H__
 
 #include <set>
 
 #include "base/basictypes.h"
@@ skipping 607 matching lines @@
 
 template <class T, typename Arg1, typename Arg2,
           typename Arg3, typename Arg4, typename Arg5>
 typename Callback5<Arg1, Arg2, Arg3, Arg4, Arg5>::Type* NewCallback(
     T* object,
     void (T::*method)(Arg1, Arg2, Arg3, Arg4, Arg5)) {
   return new CallbackImpl<T, void (T::*)(Arg1, Arg2, Arg3, Arg4, Arg5),
       Tuple5<Arg1, Arg2, Arg3, Arg4, Arg5> >(object, method);
 }
 
+// An UnboundMethod is a wrapper for a method where the actual object is
+// provided at Run dispatch time.
+template <class T, class Method, class Params>
+class UnboundMethod {
+ public:
+  UnboundMethod(Method m, Params p) : m_(m), p_(p) {}
+  void Run(T* obj) const {
+    DispatchToMethod(obj, m_, p_);
+  }
+ private:
+  Method m_;
+  Params p_;
+};
+
 #endif  // BASE_TASK_H__