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..65d80351b10ff3cb39bee78a59fd03824da72fcd 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 +38,20 @@ 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.  Returns true if |task| is posted.
   virtual bool PostTaskWithSequence(std::unique_ptr<Task> task,

[robliao, 2016/04/25 21:42:38]

Similarly, should we instead have PostSingleThreadedTaskWithSequence?

[fdoray, 2016/04/25 22:34:44]

danakj@: What is your take on this? I think that you like having a single post
task flow.

I'd like to avoid duplicating the code in PostTaskWithSequence. That means that
if we add PostSingleThreadedTaskWithSequence, we need an helper function which
will make it hard to understand the post task flow.

If we add PostSingleThreadedTaskWithSequence, we probably also need to add
PostSingleThreadedTaskWithSequenceNow.

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

+1 to single post task flow.

-                                    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. The scheduler's

[gab, 2016/04/25 21:00:20]

Add a note that SchedulerThreadPool has to be the owner of SchedulerWorkerThread
(and then DCHECK that this is true in the impl)?

[fdoray, 2016/04/25 22:34:44]

Done.

+  // 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