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

base/task_scheduler/task_scheduler.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_TASK_SCHEDULER_TASK_SCHEDULER_H_
 #define BASE_TASK_SCHEDULER_TASK_SCHEDULER_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/base_export.h"
 #include "base/callback_forward.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner.h"
 #include "base/single_thread_task_runner.h"
 #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;
 }
 
 namespace tracked_objects {
 class Location;
 }
 
 namespace base {
@@ skipping 35 matching lines @@
   // scheduling tasks using |traits|. Tasks run one at a time in posting order.
   virtual scoped_refptr<SequencedTaskRunner>
   CreateSequencedTaskRunnerWithTraits(const TaskTraits& traits) = 0;
 
   // Returns a SingleThreadTaskRunner whose PostTask invocations result in
   // scheduling tasks using |traits|. Tasks run on a single thread in posting
   // order.
   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. 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.
+  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;
 
   // Synchronously shuts down the scheduler. Once this is called, only tasks
   // posted with the BLOCK_SHUTDOWN behavior will be run. When this returns:
   // - All SKIP_ON_SHUTDOWN tasks that were already running have completed their
   //   execution.
   // - All posted BLOCK_SHUTDOWN tasks have completed their execution.
   // - CONTINUE_ON_SHUTDOWN tasks might still be running.
   // Note that an implementation can keep threads and other resources alive to
@@ skipping 70 matching lines @@
   // each process n/GetMaxConcurrentTasksWithTraitsDeprecated() items.
   //
   // TODO(fdoray): Remove this method. https://crbug.com/687264
   virtual int GetMaxConcurrentTasksWithTraitsDeprecated(
       const TaskTraits& traits) const = 0;
 };
 
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_TASK_SCHEDULER_H_