Replace NULL with nullptr in all C++ files.

webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.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 35 matching lines @@
 
     if (dwmapi_library_) {
       composition_func_ = reinterpret_cast<DwmEnableCompositionFunc>(
           GetProcAddress(dwmapi_library_, "DwmEnableComposition"));
     }
   }
 }
 
 ScreenCapturerWinGdi::~ScreenCapturerWinGdi() {
   if (desktop_dc_)
-    ReleaseDC(NULL, desktop_dc_);
+    ReleaseDC(nullptr, desktop_dc_);
   if (memory_dc_)
     DeleteDC(memory_dc_);
 
   // Restore Aero.
   if (composition_func_)
     (*composition_func_)(DWM_EC_ENABLECOMPOSITION);
 
   if (dwmapi_library_)
     FreeLibrary(dwmapi_library_);
 }
@@ skipping 54 matching lines @@
     (*composition_func_)(DWM_EC_DISABLECOMPOSITION);
 }
 
 void ScreenCapturerWinGdi::PrepareCaptureResources() {
   // Switch to the desktop receiving user input if different from the current
   // one.
   std::unique_ptr<Desktop> input_desktop(Desktop::GetInputDesktop());
   if (input_desktop && !desktop_.IsSame(*input_desktop)) {
     // Release GDI resources otherwise SetThreadDesktop will fail.
     if (desktop_dc_) {
-      ReleaseDC(NULL, desktop_dc_);
+      ReleaseDC(nullptr, desktop_dc_);
       desktop_dc_ = nullptr;
     }
 
     if (memory_dc_) {
       DeleteDC(memory_dc_);
       memory_dc_ = nullptr;
     }
 
     // If SetThreadDesktop() fails, the thread is still assigned a desktop.
     // So we can continue capture screen bits, just from the wrong desktop.
     desktop_.SetThreadDesktop(input_desktop.release());
 
     // Re-assert our vote to disable Aero.
     // See crbug.com/124018 and crbug.com/129906.
     if (composition_func_) {
       (*composition_func_)(DWM_EC_DISABLECOMPOSITION);
     }
   }
 
   // If the display bounds have changed then recreate GDI resources.
   // TODO(wez): Also check for pixel format changes.
   DesktopRect screen_rect(DesktopRect::MakeXYWH(
       GetSystemMetrics(SM_XVIRTUALSCREEN),
       GetSystemMetrics(SM_YVIRTUALSCREEN),
       GetSystemMetrics(SM_CXVIRTUALSCREEN),
       GetSystemMetrics(SM_CYVIRTUALSCREEN)));
   if (!screen_rect.equals(desktop_dc_rect_)) {
     if (desktop_dc_) {
-      ReleaseDC(NULL, desktop_dc_);
+      ReleaseDC(nullptr, desktop_dc_);
       desktop_dc_ = nullptr;
     }
     if (memory_dc_) {
       DeleteDC(memory_dc_);
       memory_dc_ = nullptr;
     }
     desktop_dc_rect_ = DesktopRect();
   }
 
   if (!desktop_dc_) {
@@ skipping 51 matching lines @@
   }
 
   // Select back the previously selected object to that the device contect
   // could be destroyed independently of the bitmap if needed.
   SelectObject(memory_dc_, previous_object);
 
   return result;
 }
 
 }  // namespace webrtc