Replace NULL with nullptr in all C++ files.

webrtc/modules/desktop_capture/screen_capturer_mac_unittest.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.
  */
 
@@ skipping 56 matching lines @@
     std::unique_ptr<DesktopFrame>* frame) {
   EXPECT_EQ(result, DesktopCapturer::Result::SUCCESS);
 
   MacDesktopConfiguration config = MacDesktopConfiguration::GetCurrent(
       MacDesktopConfiguration::BottomLeftOrigin);
   int width = config.pixel_bounds.width();
   int height = config.pixel_bounds.height();
 
   EXPECT_EQ(width, (*frame)->size().width());
   EXPECT_EQ(height, (*frame)->size().height());
-  EXPECT_TRUE((*frame)->data() != NULL);
+  EXPECT_TRUE((*frame)->data() != nullptr);
   // Depending on the capture method, the screen may be flipped or not, so
   // the stride may be positive or negative.
   EXPECT_EQ(static_cast<int>(sizeof(uint32_t) * width),
             abs((*frame)->stride()));
 }
 
 TEST_F(ScreenCapturerMacTest, Capture) {
   EXPECT_CALL(callback_,
               OnCaptureResultPtr(DesktopCapturer::Result::SUCCESS, _))
       .Times(2)
       .WillOnce(Invoke(this, &ScreenCapturerMacTest::CaptureDoneCallback1))
       .WillOnce(Invoke(this, &ScreenCapturerMacTest::CaptureDoneCallback2));
 
   SCOPED_TRACE("");
   capturer_->Start(&callback_);
 
   // Check that we get an initial full-screen updated.
   capturer_->CaptureFrame();
 
   // Check that subsequent dirty rects are propagated correctly.
   capturer_->CaptureFrame();
 }
 
 }  // namespace webrtc