Replace NULL with nullptr in all C++ files.

webrtc/modules/desktop_capture/mac/window_list_utils.cc

 /*
  *  Copyright (c) 2014 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 85 matching lines @@
       }
     }
   }
 
   return fullscreen;
 }
 
 // Returns true if the window is minimized.
 bool IsWindowMinimized(CGWindowID id) {
   CFArrayRef window_id_array =
-      CFArrayCreate(NULL, reinterpret_cast<const void **>(&id), 1, NULL);
+      CFArrayCreate(nullptr, reinterpret_cast<const void**>(&id), 1, nullptr);
   CFArrayRef window_array =
       CGWindowListCreateDescriptionFromArray(window_id_array);
   bool minimized = false;
 
   if (window_array && CFArrayGetCount(window_array)) {
     CFDictionaryRef window = reinterpret_cast<CFDictionaryRef>(
         CFArrayGetValueAtIndex(window_array, 0));
     CFBooleanRef on_screen =  reinterpret_cast<CFBooleanRef>(
         CFDictionaryGetValue(window, kCGWindowIsOnscreen));
 
     minimized = !on_screen;
   }
 
   CFRelease(window_id_array);
   CFRelease(window_array);
 
   return minimized;
 }
 
 
 
 }  // namespace webrtc