replace NULL->nullptr in src/remoting.

remoting/protocol/connection_to_client.cc

Index: remoting/protocol/connection_to_client.cc
diff --git a/remoting/protocol/connection_to_client.cc b/remoting/protocol/connection_to_client.cc
index 2135190b809257605ca11267eebe8b59efc4ef14..536fa75255de21f9d602a2ff929f0237162d2125 100644
--- a/remoting/protocol/connection_to_client.cc
+++ b/remoting/protocol/connection_to_client.cc
@@ -19,10 +19,10 @@ namespace remoting {
 namespace protocol {
 
 ConnectionToClient::ConnectionToClient(protocol::Session* session)
-    : handler_(NULL),
-      clipboard_stub_(NULL),
-      host_stub_(NULL),
-      input_stub_(NULL),
+    : handler_(nullptr),
+      clipboard_stub_(nullptr),
+      host_stub_(nullptr),
+      input_stub_(nullptr),
       session_(session) {
   session_->SetEventHandler(this);
 }