Handle delayed tasks more natively in the scheduler

cc/test/ordered_simple_task_runner.cc

Index: cc/test/ordered_simple_task_runner.cc
diff --git a/cc/test/ordered_simple_task_runner.cc b/cc/test/ordered_simple_task_runner.cc
index e337909315f3f807c059b96cee07aeb314f736bd..9fc22aded6d73a1d0bee912fe0fcf275bb3910b4 100644
--- a/cc/test/ordered_simple_task_runner.cc
+++ b/cc/test/ordered_simple_task_runner.cc
@@ -127,6 +127,10 @@ bool OrderedSimpleTaskRunner::RunsTasksOnCurrentThread() const {
   return true;
 }
 
+size_t OrderedSimpleTaskRunner::NumPendingTasks() const {
+  return pending_tasks_.size();
+}
+
 bool OrderedSimpleTaskRunner::HasPendingTasks() const {
   return pending_tasks_.size() > 0;
 }