scheduler: Remove task observer shenanigans

components/scheduler/child/scheduler_task_runner_delegate_impl.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 COMPONENTS_SCHEDULER_CHILD_SCHEDULER_TASK_RUNNER_DELEGATE_IMPL_H_
 #define COMPONENTS_SCHEDULER_CHILD_SCHEDULER_TASK_RUNNER_DELEGATE_IMPL_H_
 
 #include "base/message_loop/message_loop.h"
 #include "components/scheduler/child/scheduler_task_runner_delegate.h"
 #include "components/scheduler/scheduler_export.h"
@@ skipping 12 matching lines @@
       scoped_refptr<base::SingleThreadTaskRunner> task_runner) override;
   void RestoreDefaultTaskRunner() override;
   bool PostDelayedTask(const tracked_objects::Location& from_here,
                        const base::Closure& task,
                        base::TimeDelta delay) override;
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
                                   const base::Closure& task,
                                   base::TimeDelta delay) override;
   bool RunsTasksOnCurrentThread() const override;
   bool IsNested() const override;
-  void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer) override;
-  void RemoveTaskObserver(
-      base::MessageLoop::TaskObserver* task_observer) override;
 
  protected:
   ~SchedulerTaskRunnerDelegateImpl() override;
 
  private:
   explicit SchedulerTaskRunnerDelegateImpl(base::MessageLoop* message_loop);
 
   // Not owned.
   base::MessageLoop* message_loop_;
   scoped_refptr<SingleThreadTaskRunner> message_loop_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(SchedulerTaskRunnerDelegateImpl);
 };
 
 }  // namespace scheduler
 
 #endif  // COMPONENTS_SCHEDULER_CHILD_SCHEDULER_TASK_RUNNER_DELEGATE_IMPL_H_