Revert of base: Remove use of MessageLoopProxy

base/test/sequenced_worker_pool_owner.cc

Index: base/test/sequenced_worker_pool_owner.cc
diff --git a/base/test/sequenced_worker_pool_owner.cc b/base/test/sequenced_worker_pool_owner.cc
index b0d8b7a1adb084d0fcd78c037acfacd91c643944..4486323344219db6e344ebe8135bd4ae8e922e5b 100644
--- a/base/test/sequenced_worker_pool_owner.cc
+++ b/base/test/sequenced_worker_pool_owner.cc
@@ -6,7 +6,6 @@
 
 #include "base/location.h"
 #include "base/message_loop/message_loop.h"
-#include "base/single_thread_task_runner.h"
 
 namespace base {
 
@@ -51,8 +50,9 @@
 }
 
 void SequencedWorkerPoolOwner::OnDestruct() {
-  constructor_message_loop_->task_runner()->PostTask(
-      FROM_HERE, constructor_message_loop_->QuitWhenIdleClosure());
+  constructor_message_loop_->PostTask(
+      FROM_HERE,
+      constructor_message_loop_->QuitWhenIdleClosure());
 }
 
 }  // namespace base