Replace NULL with nullptr in all C++ files.

webrtc/test/gl/gl_renderer.cc

 /*
  *  Copyright (c) 2013 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.
  */
 
 #include "webrtc/test/gl/gl_renderer.h"
 
 #include <string.h>
 
 #include "webrtc/base/checks.h"
 #include "webrtc/common_video/libyuv/include/webrtc_libyuv.h"
 
 namespace webrtc {
 namespace test {
 
 GlRenderer::GlRenderer()
-    : is_init_(false), buffer_(NULL), width_(0), height_(0) {}
+    : is_init_(false), buffer_(nullptr), width_(0), height_(0) {}
 
 void GlRenderer::Init() {
   RTC_DCHECK(!is_init_);
   is_init_ = true;
 
   glGenTextures(1, &texture_);
 }
 
 void GlRenderer::Destroy() {
   if (!is_init_) {
     return;
   }
 
   is_init_ = false;
 
   delete[] buffer_;
-  buffer_ = NULL;
+  buffer_ = nullptr;
 
   glDeleteTextures(1, &texture_);
 }
 
 void GlRenderer::ResizeViewport(size_t width, size_t height) {
   // TODO(pbos): Aspect ratio, letterbox the video.
   glViewport(0, 0, width, height);
 
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
@@ skipping 53 matching lines @@
     glTexCoord2f(1.0f, 0.0f);
     glVertex3f(1.0f, 0.0f, 0.0f);
   }
   glEnd();
 
   glBindTexture(GL_TEXTURE_2D, 0);
   glFlush();
 }
 }  // test
 }  // webrtc