Switch usage of _DEBUG macro to NDEBUG.

webrtc/base/thread.cc

 /*
  *  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 327 matching lines @@
 
 bool Thread::SetAllowBlockingCalls(bool allow) {
   ASSERT(IsCurrent());
   bool previous = blocking_calls_allowed_;
   blocking_calls_allowed_ = allow;
   return previous;
 }
 
 // static
 void Thread::AssertBlockingIsAllowedOnCurrentThread() {
-#ifdef _DEBUG
+#if !defined(NDEBUG)
   Thread* current = Thread::Current();
   ASSERT(!current || current->blocking_calls_allowed_);
 #endif
 }
 
 void* Thread::PreRun(void* pv) {
   ThreadInit* init = static_cast<ThreadInit*>(pv);
   ThreadManager::Instance()->SetCurrentThread(init->thread);
   rtc::SetCurrentThreadName(init->thread->name_.c_str());
 #if __has_feature(objc_arc)
@@ skipping 240 matching lines @@
   if (SUCCEEDED(hr)) {
     Thread::Run();
     CoUninitialize();
   } else {
     LOG(LS_ERROR) << "CoInitialize failed, hr=" << hr;
   }
 }
 #endif
 
 }  // namespace rtc