replace NULL->nullptr in src/remoting.

remoting/host/single_window_input_injector_mac.cc

Index: remoting/host/single_window_input_injector_mac.cc
diff --git a/remoting/host/single_window_input_injector_mac.cc b/remoting/host/single_window_input_injector_mac.cc
index ecc6f530306399083636f6ce198bc97ca6aae08d..3fac4ffac0c7c54ea03c2edaa6eaf4e78c89f772 100644
--- a/remoting/host/single_window_input_injector_mac.cc
+++ b/remoting/host/single_window_input_injector_mac.cc
@@ -120,12 +120,12 @@ CGRect SingleWindowInputInjectorMac::FindCGRectOfWindow() {
   CGRect rect;
   CGWindowID ids[1] = {window_id_};
   base::ScopedCFTypeRef<CFArrayRef> window_id_array(
-      CFArrayCreate(NULL, reinterpret_cast<const void **>(&ids), 1, NULL));
+      CFArrayCreate(nullptr, reinterpret_cast<const void**>(&ids), 1, nullptr));
 
   base::ScopedCFTypeRef<CFArrayRef> window_array(
       CGWindowListCreateDescriptionFromArray(window_id_array));
 
-  if (window_array == NULL || CFArrayGetCount(window_array) == 0) {
+  if (window_array == nullptr || CFArrayGetCount(window_array) == 0) {
     // Could not find the window. It might have been closed.
     LOG(ERROR) << "Specified window to stream not found for id: "
                << window_id_;