Switch usage of _DEBUG macro to NDEBUG.

webrtc/base/taskrunner.h

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 26 matching lines @@
   //
   // On Windows, GetSystemTimeAsFileTime is the typical implementation.
   virtual int64_t CurrentTime() = 0;
 
   void StartTask(Task *task);
   void RunTasks();
   void PollTasks();
 
   void UpdateTaskTimeout(Task* task, int64_t previous_task_timeout_time);
 
-#ifdef _DEBUG
+#if !defined(NDEBUG)
   bool is_ok_to_delete(Task* task) {
     return task == deleting_task_;
   }
 
   void IncrementAbortCount() {
     ++abort_count_;
   }
 
   void DecrementAbortCount() {
     --abort_count_;
@@ skipping 22 matching lines @@
     // by default, do nothing.
   }
 
  private:
   void InternalRunTasks(bool in_destructor);
   void CheckForTimeoutChange(int64_t previous_timeout_time);
 
   std::vector<Task *> tasks_;
   Task *next_timeout_task_;
   bool tasks_running_;
-#ifdef _DEBUG
+#if !defined(NDEBUG)
   int abort_count_;
   Task* deleting_task_;
 #endif
 
   void RecalcNextTimeout(Task *exclude_task);
 };
 
 } // namespace rtc
 
 #endif  // TASK_BASE_TASKRUNNER_H__