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/cefclient/browser/browser_window_std_gtk.cc

@@ -43,7 +43,7 @@ void SetXWindowVisible(XDisplay* xdisplay, ::Window xwindow, bool visible) {
 
   if (!visible) {
     // Set the hidden property state value.
-    scoped_ptr<Atom[]> data(new Atom[1]);
+    std::unique_ptr<Atom[]> data(new Atom[1]);
     data[0] = atoms[2];
 
     XChangeProperty(xdisplay, xwindow,
@@ -59,7 +59,7 @@ void SetXWindowVisible(XDisplay* xdisplay, ::Window xwindow, bool visible) {
                     atoms[0],  // name
                     atoms[1],  // type
                     32,        // size in bits of items in 'value'
-                    PropModeReplace, NULL,
+                    PropModeReplace, nullptr,
                     0);  // num items
   }
 }
@@ -182,7 +182,7 @@ ClientWindowHandle BrowserWindowStdGtk::GetWindowHandle() const {
 
   // There is no GtkWidget* representation of this object.
   NOTREACHED();
-  return NULL;
+  return nullptr;
 }
 
 }  // namespace client