Add SequencedWorkerPool.IsRunningSequenceOnCurrentThread so callers can make stronger assertions ab…

base/threading/sequenced_worker_pool.cc

Index: base/threading/sequenced_worker_pool.cc
===================================================================
--- base/threading/sequenced_worker_pool.cc	(revision 128981)
+++ base/threading/sequenced_worker_pool.cc	(working copy)
@@ -59,8 +59,17 @@
   // SimpleThread implementation. This actually runs the background thread.
   virtual void Run() OVERRIDE;
 
+  void set_running_sequence(SequenceToken token) {
+    running_sequence_ = token;
+  }
+
+  SequenceToken running_sequence() const {
+    return running_sequence_;
+  }
+
  private:
   scoped_refptr<SequencedWorkerPool> worker_pool_;
+  SequenceToken running_sequence_;
 
   DISALLOW_COPY_AND_ASSIGN(Worker);
 };
@@ -92,6 +101,8 @@
 
   bool RunsTasksOnCurrentThread() const;
 
+  bool IsRunningSequenceOnCurrentThread(SequenceToken sequence_token) const;
+
   void FlushForTesting();
 
   void SignalHasWorkForTesting();
@@ -350,6 +361,15 @@
   return ContainsKey(threads_, PlatformThread::CurrentId());
 }
 
+bool SequencedWorkerPool::Inner::IsRunningSequenceOnCurrentThread(
+    SequenceToken sequence_token) const {
+  AutoLock lock(lock_);
+  ThreadMap::const_iterator found = threads_.find(PlatformThread::CurrentId());
+  if (found == threads_.end())
+    return false;
+  return found->second->running_sequence().Equals(sequence_token);
+}
+
 void SequencedWorkerPool::Inner::FlushForTesting() {
   AutoLock lock(lock_);
   while (!IsIdle())
@@ -427,8 +447,13 @@
           if (new_thread_id)
             FinishStartingAdditionalThread(new_thread_id);
 
+          this_worker->set_running_sequence(
+              SequenceToken(task.sequence_token_id));
+
           task.task.Run();
 
+          this_worker->set_running_sequence(SequenceToken());
+
           // Make sure our task is erased outside the lock for the same reason
           // we do this with delete_these_oustide_lock.
           task.task = Closure();
@@ -788,6 +813,11 @@
   return inner_->RunsTasksOnCurrentThread();
 }
 
+bool SequencedWorkerPool::IsRunningSequenceOnCurrentThread(
+    SequenceToken sequence_token) const {
+  return inner_->IsRunningSequenceOnCurrentThread(sequence_token);
+}
+
 void SequencedWorkerPool::FlushForTesting() {
   inner_->FlushForTesting();
 }