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

cc/test/ordered_simple_task_runner.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/test/ordered_simple_task_runner.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <limits>
@@ skipping 180 matching lines @@
   modifiable_conditions.push_back(TaskRunCountBelow(max_tasks_));
 
   // If to advance now or not
   if (!advance_now_) {
     modifiable_conditions.push_back(NowBefore(now_src_->NowTicks()));
   } else {
     modifiable_conditions.push_back(AdvanceNow());
   }
 
   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 =
              modifiable_conditions.begin();
          it != modifiable_conditions.end();
          it++) {
       condition_success = it->Run();
       if (!condition_success)
         break;
     }
@@ skipping 127 matching lines @@
 
 bool OrderedSimpleTaskRunner::AdvanceNowCallback() {
   base::TimeTicks next_task_time = NextTaskTime();
   if (now_src_->NowTicks() < next_task_time) {
     now_src_->Advance(next_task_time - now_src_->NowTicks());
   }
   return true;
 }
 
 }  // namespace cc