Various fixes related to the C++11/14 update (see issue #3140)

- Convert scoped_ptr to std::unique_ptr from <memory>
- Convert arraysize to base::size from include/base/cef_cxx17_backports.h
- Convert NULL to nullptr
- Include include/base/cef_callback.h instead of include/base/cef_bind.h
- Implicit conversion of CefRefPtr<T> or scoped_refptr<T> to T* is gone;
  use .get() instead

See the issue for additional details.

tests/cefsimple/simple_app.cc

@@ -119,7 +119,7 @@ void SimpleApp::OnContextInitialized() {
 #if defined(OS_WIN)
     // On Windows we need to specify certain flags that will be passed to
     // CreateWindowEx().
-    window_info.SetAsPopup(NULL, "cefsimple");
+    window_info.SetAsPopup(nullptr, "cefsimple");
 #endif
 
     // Create the first browser window.