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

base/task_scheduler/task_scheduler.h

Index: base/task_scheduler/task_scheduler.h
diff --git a/base/task_scheduler/task_scheduler.h b/base/task_scheduler/task_scheduler.h
index 4b07c88998ba922f46914f7f88055b939e1947cc..88b23379c7e04d16414d33cb24201b59f9ca4147 100644
--- a/base/task_scheduler/task_scheduler.h
+++ b/base/task_scheduler/task_scheduler.h
@@ -17,6 +17,7 @@
 #include "base/task_runner.h"
 #include "base/task_scheduler/task_traits.h"
 #include "base/time/time.h"
+#include "build/build_config.h"
 
 namespace gin {
 class V8Platform;
@@ -72,6 +73,17 @@ class BASE_EXPORT TaskScheduler {
   virtual scoped_refptr<SingleThreadTaskRunner>
   CreateSingleThreadTaskRunnerWithTraits(const TaskTraits& traits) = 0;
 
+#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
+  // with different Single-Threaded Apartments so care should be taken to make
+  // sure COM pointers are not smuggled across apartments.
+  virtual scoped_refptr<SingleThreadTaskRunner>
+  CreateCOMSTATaskRunnerWithTraits(const TaskTraits& traits) = 0;
+#endif  // defined(OS_WIN)
+
   // Returns a vector of all histograms available in this task scheduler.
   virtual std::vector<const HistogramBase*> GetHistograms() const = 0;