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

base/task_scheduler/post_task.h

Index: base/task_scheduler/post_task.h
diff --git a/base/task_scheduler/post_task.h b/base/task_scheduler/post_task.h
index 3174f06d63b11369079b84791aea2fb425bd23eb..dcb5bc0b0a3af06d65d577c5ba4c7876b03b7589 100644
--- a/base/task_scheduler/post_task.h
+++ b/base/task_scheduler/post_task.h
@@ -18,6 +18,7 @@
 #include "base/task_runner.h"
 #include "base/task_scheduler/task_traits.h"
 #include "base/time/time.h"
+#include "build/build_config.h"
 
 namespace base {
 
@@ -171,6 +172,19 @@ CreateSequencedTaskRunnerWithTraits(const TaskTraits& traits);
 BASE_EXPORT scoped_refptr<SingleThreadTaskRunner>
 CreateSingleThreadTaskRunnerWithTraits(const TaskTraits& traits);
 
+#if defined(OS_WIN)
+// Returns a SingleThreadTaskRunner whose PostTask invocations result in
+// scheduling tasks using |traits| in a COM Single-Threaded Apartment. Tasks run
+// in the same Single-Threaded Apartment in posting order for the returned
+// SingleThreadTaskRunner. There is not necessarily a one-to-one correspondence
+// between SingleThreadTaskRunners and Single-Threaded Apartments. The
+// implementation is free to share apartments or create new apartments as
+// necessary. In either case, care should be taken to make sure COM pointers are
+// not smuggled across apartments.
+BASE_EXPORT scoped_refptr<SingleThreadTaskRunner>
+CreateCOMSTATaskRunnerWithTraits(const TaskTraits& traits);
+#endif  // defined(OS_WIN)
+
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_POST_TASK_H_