TaskScheduler [11] Support ExecutionMode::SINGLE_THREADED.

base/task_scheduler/scheduler_thread_pool.h

Index: base/task_scheduler/scheduler_thread_pool.h
diff --git a/base/task_scheduler/scheduler_thread_pool.h b/base/task_scheduler/scheduler_thread_pool.h
index 2451474d297209912dfae6a491731871a7e59e49..8c3e9a86e1f339906d6a8b3aaa968ac7ba1bda44 100644
--- a/base/task_scheduler/scheduler_thread_pool.h
+++ b/base/task_scheduler/scheduler_thread_pool.h
@@ -17,6 +17,7 @@
 namespace base {
 namespace internal {
 
+class SchedulerWorkerThread;
 struct SequenceSortKey;
 
 // Interface for a thread pool.
@@ -37,16 +38,22 @@ class BASE_EXPORT SchedulerThreadPool {
   virtual void ReEnqueueSequence(scoped_refptr<Sequence> sequence,
                                  const SequenceSortKey& sequence_sort_key) = 0;
 
-  // Posts |task| to be executed as part of |sequence|.  Returns true if |task|
-  // is posted.
+  // Posts |task| to be executed as part of |sequence|. |task| will run on
+  // |worker_thread| if specified (must be owned by this thread pool).  Returns

[gab, 2016/04/26 11:46:27]

As-is it's unclear whether the comments in parens refers to |task| or
|worker_thread| IMO. How about:

"If |worker_thread| is non-null, |task| will be scheduled to run on it
specifically (note: |worker_thread| must be owned by this SchedulerThreadPool);
otherwise, |task| will be added to the pending shared work"

[fdoray, 2016/04/26 14:56:47]

Done.

+  // true if |task| is posted.
   virtual bool PostTaskWithSequence(std::unique_ptr<Task> task,
-                                    scoped_refptr<Sequence> sequence) = 0;
-
-  // Posts |task| to be executed by this thread pool as part of |sequence|. The
-  // scheduler's TaskTracker must have allowed |task| to be posted before this
-  // is called. This must only be called after |task|'s delayed run time.
-  virtual void PostTaskWithSequenceNow(std::unique_ptr<Task> task,
-                                       scoped_refptr<Sequence> sequence) = 0;
+                                    scoped_refptr<Sequence> sequence,
+                                    SchedulerWorkerThread* worker_thread) = 0;
+
+  // Posts |task| to be executed by this thread pool as part of |sequence|.
+  // |task| will run on |worker_thread| if specified (must be owned by this
+  // thread pool). The scheduler's TaskTracker must have allowed |task| to be
+  // posted before this is called. This must only be called after |task|'s
+  // delayed run time.
+  virtual void PostTaskWithSequenceNow(
+      std::unique_ptr<Task> task,
+      scoped_refptr<Sequence> sequence,
+      SchedulerWorkerThread* worker_thread) = 0;
 };
 
 }  // namespace internal