replace NULL->nullptr in src/remoting.

remoting/host/video_frame_recorder.cc

 // 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.
 
 #include "remoting/host/video_frame_recorder.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
@@ skipping 142 matching lines @@
   content_bytes_ = 0;
 
   // Tell the wrapper to stop recording and posting frames to us.
   if (encoder_task_runner_.get()) {
     encoder_task_runner_->PostTask(FROM_HERE,
         base::Bind(&RecordingVideoEncoder::set_enable_recording,
                    recording_encoder_, false));
   }
 
   // Detach this recorder from the calling and encode threads.
-  caller_task_runner_ = NULL;
-  encoder_task_runner_ = NULL;
+  caller_task_runner_ = nullptr;
+  encoder_task_runner_ = nullptr;
 }
 
 void VideoFrameRecorder::SetEnableRecording(bool enable_recording) {
   DCHECK(!caller_task_runner_.get() ||
          caller_task_runner_->BelongsToCurrentThread());
 
   if (enable_recording_ == enable_recording) {
     return;
   }
   enable_recording_ = enable_recording;
@@ skipping 64 matching lines @@
   if (content_bytes_ + frame_bytes > max_content_bytes_) {
     return;
   }
 
   // Store the frame and update the content byte count.
   recorded_frames_.push_back(frame.release());
   content_bytes_ += frame_bytes;
 }
 
 }  // namespace remoting