TaskScheduler [8] SEQUENCED TaskRunners in SchedulerThreadPool.

base/task_scheduler/scheduler_thread_pool.cc

Index: base/task_scheduler/scheduler_thread_pool.cc
diff --git a/base/task_scheduler/scheduler_thread_pool.cc b/base/task_scheduler/scheduler_thread_pool.cc
index 62b6562374f007441e4b317b62163cf6fbc20d1a..4f66fbc0456d4e02c46c190e7e2fbc6f58a68c87 100644
--- a/base/task_scheduler/scheduler_thread_pool.cc
+++ b/base/task_scheduler/scheduler_thread_pool.cc
@@ -11,6 +11,7 @@
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
+#include "base/sequenced_task_runner.h"
 #include "base/task_scheduler/task_tracker.h"
 
 namespace base {
@@ -59,6 +60,49 @@ class SchedulerParallelTaskRunner : public TaskRunner {
   DISALLOW_COPY_AND_ASSIGN(SchedulerParallelTaskRunner);
 };
 
+// A task runner that runs tasks with the SEQUENCED ExecutionMode.
+class SchedulerSequencedTaskRunner : public SequencedTaskRunner {
+ public:
+  SchedulerSequencedTaskRunner(const TaskTraits& traits,
+                               PriorityQueue* priority_queue,
+                               TaskTracker* task_tracker)
+      : traits_(traits),
+        priority_queue_(priority_queue),
+        task_tracker_(task_tracker) {}
+
+  // SequencedTaskRunner:
+  bool PostDelayedTask(const tracked_objects::Location& from_here,
+                       const Closure& closure,
+                       TimeDelta delay) override {
+    // TODO(fdoray): Support delayed tasks.
+    DCHECK(delay.is_zero());
+    PostTaskHelper(WrapUnique(new Task(from_here, closure, traits_)), sequence_,
+                   priority_queue_, task_tracker_);
+    return true;
+  }
+
+  bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
+                                  const Closure& closure,
+                                  base::TimeDelta delay) override {
+    // Tasks are never nested within the task scheduler.
+    return PostDelayedTask(from_here, closure, delay);
+  }
+
+  bool RunsTasksOnCurrentThread() const override {
+    return g_current_shared_priority_queue.Get().Get() == priority_queue_;
+  }
+
+ private:
+  ~SchedulerSequencedTaskRunner() override = default;
+
+  const TaskTraits traits_;
+  const scoped_refptr<Sequence> sequence_ = new Sequence;
+  PriorityQueue* const priority_queue_;
+  TaskTracker* const task_tracker_;
+
+  DISALLOW_COPY_AND_ASSIGN(SchedulerSequencedTaskRunner);
+};
+
 void PostTaskCallback(scoped_refptr<Sequence> sequence,
                       PriorityQueue* priority_queue,
                       std::unique_ptr<Task> task) {
@@ -107,6 +151,9 @@ scoped_refptr<TaskRunner> SchedulerThreadPool::CreateTaskRunnerWithTraits(
           traits, &shared_priority_queue_, task_tracker_));
 
     case ExecutionMode::SEQUENCED:
+      return make_scoped_refptr(new SchedulerSequencedTaskRunner(
+          traits, &shared_priority_queue_, task_tracker_));
+
     case ExecutionMode::SINGLE_THREADED:
       NOTIMPLEMENTED();
       return nullptr;