Add Support to Get a COM STA Task Runner from the Task Scheduler API

base/test/scoped_task_scheduler.h

Index: base/test/scoped_task_scheduler.h
diff --git a/base/test/scoped_task_scheduler.h b/base/test/scoped_task_scheduler.h
index 4ac2bb541be2f6ec83ac51fbaa81799ab678ff3f..785443954b56e34097c3b0ec94f37dffaabdee1b 100644
--- a/base/test/scoped_task_scheduler.h
+++ b/base/test/scoped_task_scheduler.h
@@ -57,8 +57,9 @@ class ScopedTaskScheduler {
   ScopedTaskScheduler();
 
   // Registers a synchronous TaskScheduler on a thread that already has a
-  // |message_loop|. Calling RunLoop::Run/RunUntilIdle() on the thread where
-  // this lives runs the MessageLoop and TaskScheduler tasks in posting order.
+  // |message_loop| assumed to be associated with the caller's thread. Calling
+  // RunLoop::Run/RunUntilIdle() on the thread where this lives runs the
+  // MessageLoop and TaskScheduler tasks in posting order.
   //
   // In general, you don't need a ScopedTaskScheduler and a MessageLoop because
   // ScopedTaskScheduler provides most MessageLoop features.