Replace NULL with nullptr in all C++ files.

webrtc/modules/desktop_capture/screen_drawer_win.cc

Index: webrtc/modules/desktop_capture/screen_drawer_win.cc
diff --git a/webrtc/modules/desktop_capture/screen_drawer_win.cc b/webrtc/modules/desktop_capture/screen_drawer_win.cc
index 7b1a56f84a11bb797645561728eb75abc2cc97ab..354ec6a4bc8256c2beef61e8600e31921d0b87b0 100644
--- a/webrtc/modules/desktop_capture/screen_drawer_win.cc
+++ b/webrtc/modules/desktop_capture/screen_drawer_win.cc
@@ -33,8 +33,8 @@ class ScreenDrawerLockWin : public ScreenDrawerLock {
 
 ScreenDrawerLockWin::ScreenDrawerLockWin() {
   while (true) {
-    mutex_ = CreateMutex(NULL, FALSE, kMutexName);
-    if (GetLastError() != ERROR_ALREADY_EXISTS && mutex_ != NULL) {
+    mutex_ = CreateMutex(nullptr, FALSE, kMutexName);
+    if (GetLastError() != ERROR_ALREADY_EXISTS && mutex_ != nullptr) {
       break;
     } else {
       if (mutex_) {
@@ -50,17 +50,18 @@ ScreenDrawerLockWin::~ScreenDrawerLockWin() {
 }
 
 DesktopRect GetScreenRect() {
-  HDC hdc = GetDC(NULL);
+  HDC hdc = GetDC(nullptr);
   DesktopRect rect = DesktopRect::MakeWH(GetDeviceCaps(hdc, HORZRES),
                                          GetDeviceCaps(hdc, VERTRES));
-  ReleaseDC(NULL, hdc);
+  ReleaseDC(nullptr, hdc);
   return rect;
 }
 
 HWND CreateDrawerWindow(DesktopRect rect) {
-  HWND hwnd = CreateWindowA(
-      "STATIC", "DrawerWindow", WS_POPUPWINDOW | WS_VISIBLE, rect.left(),
-      rect.top(), rect.width(), rect.height(), NULL, NULL, NULL, NULL);
+  HWND hwnd =
+      CreateWindowA("STATIC", "DrawerWindow", WS_POPUPWINDOW | WS_VISIBLE,
+                    rect.left(), rect.top(), rect.width(), rect.height(),
+                    nullptr, nullptr, nullptr, nullptr);
   SetForegroundWindow(hwnd);
   return hwnd;
 }
@@ -115,7 +116,7 @@ ScreenDrawerWin::ScreenDrawerWin()
 }
 
 ScreenDrawerWin::~ScreenDrawerWin() {
-  ReleaseDC(NULL, hdc_);
+  ReleaseDC(nullptr, hdc_);
   DestroyWindow(window_);
   // Unfortunately there is no EnableProcessWindowsGhosting() API.
 }