Replace NULL with nullptr in all C++ files.

webrtc/modules/audio_device/android/audio_manager.cc

 /*
  *  Copyright (c) 2015 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 118 matching lines @@
   // If one already has been created, return existing object instead of
   // creating a new.
   if (engine_object_.Get() != nullptr) {
     ALOGI("The OpenSL ES engine object has already been created");
     return engine_object_.Get();
   }
   // Create the engine object in thread safe mode.
   const SLEngineOption option[] = {
       {SL_ENGINEOPTION_THREADSAFE, static_cast<SLuint32>(SL_BOOLEAN_TRUE)}};
   SLresult result =
-      slCreateEngine(engine_object_.Receive(), 1, option, 0, NULL, NULL);
+      slCreateEngine(engine_object_.Receive(), 1, option, 0, nullptr, nullptr);
   if (result != SL_RESULT_SUCCESS) {
     ALOGE("slCreateEngine() failed: %s", GetSLErrorString(result));
     engine_object_.Reset();
     return nullptr;
   }
   // Realize the SL Engine in synchronous mode.
   result = engine_object_->Realize(engine_object_.Get(), SL_BOOLEAN_FALSE);
   if (result != SL_RESULT_SUCCESS) {
     ALOGE("Realize() failed: %s", GetSLErrorString(result));
     engine_object_.Reset();
@@ skipping 140 matching lines @@
   return playout_parameters_;
 }
 
 const AudioParameters& AudioManager::GetRecordAudioParameters() {
   RTC_CHECK(record_parameters_.is_valid());
   RTC_DCHECK(thread_checker_.CalledOnValidThread());
   return record_parameters_;
 }
 
 }  // namespace webrtc