[DONT COMMIT] Fix perf regression in CompositorWorkerScheduler

third_party/WebKit/Source/platform/scheduler/child/worker_scheduler.h

 // Copyright 2015 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.
 
 #ifndef THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_WORKER_SCHEDULER_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_WORKER_SCHEDULER_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 15 matching lines @@
       scoped_refptr<SchedulerTqmDelegate> main_task_runner);
 
   // Blink should use WorkerScheduler::DefaultTaskQueue instead of
   // ChildScheduler::DefaultTaskRunner.
   virtual scoped_refptr<TaskQueue> DefaultTaskQueue() = 0;
 
   // Must be called before the scheduler can be used. Does any post construction
   // initialization needed such as initializing idle period detection.
   virtual void Init() = 0;
 
-  scoped_refptr<TaskQueue> CreateUnthrottledTaskRunner(
+  virtual scoped_refptr<TaskQueue> CreateUnthrottledTaskRunner(
       TaskQueue::QueueType queue_type);
 
  protected:
   explicit WorkerScheduler(std::unique_ptr<SchedulerHelper> helper);
 
   std::unique_ptr<SchedulerHelper> helper_;
 
   DISALLOW_COPY_AND_ASSIGN(WorkerScheduler);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_WORKER_SCHEDULER_H_