replace NULL->nullptr in src/remoting.

remoting/host/shaped_desktop_capturer_unittest.cc

 // Copyright 2014 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.
 
 #include "remoting/host/shaped_desktop_capturer.h"
 
 #include "remoting/host/desktop_shape_tracker.h"
 #include "remoting/host/fake_desktop_capturer.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/webrtc/modules/desktop_capture/desktop_frame.h"
@@ skipping 24 matching lines @@
 
  private:
   webrtc::DesktopRegion shape_;
 };
 
 class ShapedDesktopCapturerTest : public testing::Test,
                                  public webrtc::DesktopCapturer::Callback {
  public:
   // webrtc::DesktopCapturer::Callback interface
   webrtc::SharedMemory* CreateSharedMemory(size_t size) override {
-    return NULL;
+    return nullptr;
   }
 
   void OnCaptureCompleted(webrtc::DesktopFrame* frame) override {
     last_frame_.reset(frame);
   }
 
   scoped_ptr<webrtc::DesktopFrame> last_frame_;
 };
 
 // Verify that captured frame have shape.
 TEST_F(ShapedDesktopCapturerTest, Basic) {
   ShapedDesktopCapturer capturer(
       make_scoped_ptr(new FakeDesktopCapturer()),
       make_scoped_ptr(new FakeDesktopShapeTracker()));
   capturer.Start(this);
   capturer.Capture(webrtc::DesktopRegion());
   ASSERT_TRUE(last_frame_.get());
   ASSERT_TRUE(last_frame_->shape());
   EXPECT_TRUE(
       FakeDesktopShapeTracker::CreateShape().Equals(*last_frame_->shape()));
 }
 
 }  // namespace remoting