replace NULL->nullptr in src/remoting.

remoting/host/it2me/it2me_native_messaging_host.cc

Index: remoting/host/it2me/it2me_native_messaging_host.cc
diff --git a/remoting/host/it2me/it2me_native_messaging_host.cc b/remoting/host/it2me/it2me_native_messaging_host.cc
index 93286b352c9371802553d18287095285f2166fb4..148dc01fb7aea09df6674da4f24d47a720cabab5 100644
--- a/remoting/host/it2me/it2me_native_messaging_host.cc
+++ b/remoting/host/it2me/it2me_native_messaging_host.cc
@@ -44,7 +44,7 @@ const remoting::protocol::NameMapElement<It2MeHostState> kIt2MeHostStates[] = {
 It2MeNativeMessagingHost::It2MeNativeMessagingHost(
     scoped_ptr<ChromotingHostContext> context,
     scoped_ptr<It2MeHostFactory> factory)
-    : client_(NULL),
+    : client_(nullptr),
       host_context_(context.Pass()),
       factory_(factory.Pass()),
       weak_factory_(this) {
@@ -69,7 +69,7 @@ It2MeNativeMessagingHost::~It2MeNativeMessagingHost() {
 
   if (it2me_host_.get()) {
     it2me_host_->Disconnect();
-    it2me_host_ = NULL;
+    it2me_host_ = nullptr;
   }
 }
 
@@ -219,7 +219,7 @@ void It2MeNativeMessagingHost::ProcessDisconnect(
 
   if (it2me_host_.get()) {
     it2me_host_->Disconnect();
-    it2me_host_ = NULL;
+    it2me_host_ = nullptr;
   }
   SendMessageToClient(response.Pass());
 }