replace NULL->nullptr in src/remoting.

remoting/host/win/rdp_client_unittest.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // ATL headers have to go first.
 #include <atlbase.h>
 #include <atlhost.h>
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 53 matching lines @@
  private:
   base::win::ScopedCOMInitializer com_initializer_;
 };
 
 RdpClientModule::RdpClientModule() {
   AtlAxWinInit();
 }
 
 RdpClientModule::~RdpClientModule() {
   AtlAxWinTerm();
-  ATL::_pAtlModule = NULL;
+  ATL::_pAtlModule = nullptr;
 }
 
 }  // namespace
 
 class RdpClientTest : public testing::Test {
  public:
   RdpClientTest();
   virtual ~RdpClientTest();
 
   virtual void SetUp() override;
@@ skipping 73 matching lines @@
       .Times(AtMost(1))
       .WillOnce(Invoke(this, &RdpClientTest::OnRdpConnected));
   EXPECT_CALL(event_handler_, OnRdpClosed())
       .Times(AtMost(1))
       .WillOnce(InvokeWithoutArgs(this, &RdpClientTest::CloseRdpClient));
 
   rdp_client_.reset(new RdpClient(
       task_runner_, task_runner_,
       webrtc::DesktopSize(kDefaultWidth, kDefaultHeight),
       terminal_id_, &event_handler_));
-  task_runner_ = NULL;
+  task_runner_ = nullptr;
 
   run_loop_.Run();
 }
 
 }  // namespace remoting