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_osr_win.cc

@@ -11,7 +11,7 @@ namespace client {
 BrowserWindowOsrWin::BrowserWindowOsrWin(BrowserWindow::Delegate* delegate,
                                          const std::string& startup_url,
                                          const OsrRendererSettings& settings)
-    : BrowserWindow(delegate), osr_hwnd_(NULL), device_scale_factor_(0) {
+    : BrowserWindow(delegate), osr_hwnd_(nullptr), device_scale_factor_(0) {
   osr_window_ = new OsrWindowWin(this, settings);
   client_handler_ = new ClientHandlerOsr(this, osr_window_.get(), startup_url);
 }