[Try # 3] Scheduler refactoring to virtually eliminate redundant DoWorks

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 9dc4bbcd2dacb680d586699576a632e286aab037..395a2a64e0d11caa4c2e9bfeeb53cedf85181a47 100644
--- a/cc/test/ordered_simple_task_runner.cc
+++ b/cc/test/ordered_simple_task_runner.cc
@@ -198,6 +198,11 @@ bool OrderedSimpleTaskRunner::RunTasksWhile(
   }
 
   while (pending_tasks_.size() > 0) {
+    // Skip canceled tasks.
+    if (pending_tasks_.begin()->task.IsCancelled()) {
+      pending_tasks_.erase(pending_tasks_.begin());
+      continue;
+    }
     // Check if we should continue to run pending tasks.
     bool condition_success = true;
     for (std::vector<base::Callback<bool(void)>>::iterator it =