Replace NULL with nullptr in all C++ files.

webrtc/modules/desktop_capture/mouse_cursor_monitor_win.cc

Index: webrtc/modules/desktop_capture/mouse_cursor_monitor_win.cc
diff --git a/webrtc/modules/desktop_capture/mouse_cursor_monitor_win.cc b/webrtc/modules/desktop_capture/mouse_cursor_monitor_win.cc
index 0a7aff1432426076fb0d09979ce173ddd447c500..d7f442f489d49c2ab4ccf308d4cb8b7f8312ac0b 100644
--- a/webrtc/modules/desktop_capture/mouse_cursor_monitor_win.cc
+++ b/webrtc/modules/desktop_capture/mouse_cursor_monitor_win.cc
@@ -65,25 +65,25 @@ class MouseCursorMonitorWin : public MouseCursorMonitor {
 MouseCursorMonitorWin::MouseCursorMonitorWin(HWND window)
     : window_(window),
       screen_(kInvalidScreenId),
-      callback_(NULL),
+      callback_(nullptr),
       mode_(SHAPE_AND_POSITION),
-      desktop_dc_(NULL) {
+      desktop_dc_(nullptr) {
   memset(&last_cursor_, 0, sizeof(CURSORINFO));
 }
 
 MouseCursorMonitorWin::MouseCursorMonitorWin(ScreenId screen)
-    : window_(NULL),
+    : window_(nullptr),
       screen_(screen),
-      callback_(NULL),
+      callback_(nullptr),
       mode_(SHAPE_AND_POSITION),
-      desktop_dc_(NULL) {
+      desktop_dc_(nullptr) {
   assert(screen >= kFullDesktopScreenId);
   memset(&last_cursor_, 0, sizeof(CURSORINFO));
 }
 
 MouseCursorMonitorWin::~MouseCursorMonitorWin() {
   if (desktop_dc_)
-    ReleaseDC(NULL, desktop_dc_);
+    ReleaseDC(nullptr, desktop_dc_);
 }
 
 void MouseCursorMonitorWin::Init(Callback* callback, Mode mode) {
@@ -93,7 +93,7 @@ void MouseCursorMonitorWin::Init(Callback* callback, Mode mode) {
   callback_ = callback;
   mode_ = mode;
 
-  desktop_dc_ = GetDC(NULL);
+  desktop_dc_ = GetDC(nullptr);
 }
 
 void MouseCursorMonitorWin::Capture() {
@@ -175,7 +175,7 @@ DesktopRect MouseCursorMonitorWin::GetScreenRect() {
   }
   DISPLAY_DEVICE device;
   device.cb = sizeof(device);
-  BOOL result = EnumDisplayDevices(NULL, screen_, &device, 0);
+  BOOL result = EnumDisplayDevices(nullptr, screen_, &device, 0);
   if (!result)
     return DesktopRect();