Replace Closure in TaskRunner::PostTask with OneShotCallback

base/debug/task_annotator.h

 // 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.
 
 #ifndef BASE_DEBUG_TASK_ANNOTATOR_H_
 #define BASE_DEBUG_TASK_ANNOTATOR_H_
 
 #include <stdint.h>
 
 #include "base/base_export.h"
 #include "base/macros.h"
 
 namespace base {
 struct PendingTask;
 namespace debug {
 
 // Implements common debug annotations for posted tasks. This includes data
 // such as task origins, queueing durations and memory usage.
 class BASE_EXPORT TaskAnnotator {
  public:
   TaskAnnotator();
   ~TaskAnnotator();
 
   // Called to indicate that a task has been queued to run in the future.
   // |queue_function| is used as the trace flow event name.
   void DidQueueTask(const char* queue_function,
                     const PendingTask& pending_task);
 
   // Run a previously queued task. |queue_function| should match what was
-  // passed into |DidQueueTask| for this task.
-  void RunTask(const char* queue_function, const PendingTask& pending_task);
+  // passed into |DidQueueTask| for this task. This resets |pending_task.task|.
+  void RunTask(const char* queue_function, PendingTask* pending_task);
 
  private:
   // Creates a process-wide unique ID to represent this task in trace events.
   // This will be mangled with a Process ID hash to reduce the likelyhood of
   // colliding with TaskAnnotator pointers on other processes.
   uint64_t GetTaskTraceID(const PendingTask& task) const;
 
   DISALLOW_COPY_AND_ASSIGN(TaskAnnotator);
 };
 
 }  // namespace debug
 }  // namespace base
 
 #endif  // BASE_DEBUG_TASK_ANNOTATOR_H_