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..024e242771eccab2cfb0dad490174c9b29579d31 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 +172,17 @@ 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. Different SingleThreadTaskRunners may be associated

[fdoray, 2017/03/27 20:11:50]

// The Single-Threaded Apartment assigned to the returned SingleThreadTaskRunner
may be shared with other SingleThreadTaskRunners.

[robliao, 2017/03/27 20:28:05]

Changed the note to...
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.

+// with different Single-Threaded Apartments so 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_