Implementation of SequencedTaskRunner based on SequencedWorkerPool.

base/threading/sequenced_worker_pool.h

Index: base/threading/sequenced_worker_pool.h
===================================================================
--- base/threading/sequenced_worker_pool.h	(revision 130053)
+++ base/threading/sequenced_worker_pool.h	(working copy)
@@ -26,6 +26,8 @@
 
 template <class T> class DeleteHelper;
 
+class SequencedTaskRunner;
+
 // A worker thread pool that enforces ordering between sets of tasks. It also
 // allows you to specify what should happen to your tasks on shutdown.
 //
@@ -152,6 +154,11 @@
   // will be created.
   SequenceToken GetNamedSequenceToken(const std::string& name);
 
+  // Returns a SequencedTaskRunner wrapper which posts to this
+  // SequencedWorkerPool using the given sequence token.
+  scoped_refptr<SequencedTaskRunner> GetSequencedTaskRunner(
+      SequenceToken token);
+
   // Posts the given task for execution in the worker pool. Tasks posted with
   // this function will execute in an unspecified order on a background thread.
   // Returns true if the task was posted. If your tasks have ordering