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/cefclient_win.cc

@@ -4,7 +4,8 @@
 
 #include <windows.h>
 
-#include "include/base/cef_scoped_ptr.h"
+#include <memory>
+
 #include "include/cef_command_line.h"
 #include "include/cef_sandbox_win.h"
 #include "tests/cefclient/browser/main_context_impl.h"
@@ -68,7 +69,7 @@ int RunMain(HINSTANCE hInstance, int nCmdShow) {
     return exit_code;
 
   // Create the main context object.
-  scoped_ptr<MainContextImpl> context(new MainContextImpl(command_line, true));
+  auto context = std::make_unique<MainContextImpl>(command_line, true);
 
   CefSettings settings;
 
@@ -84,7 +85,7 @@ int RunMain(HINSTANCE hInstance, int nCmdShow) {
   context->PopulateSettings(&settings);
 
   // Create the main message loop object.
-  scoped_ptr<MainMessageLoop> message_loop;
+  std::unique_ptr<MainMessageLoop> message_loop;
   if (settings.multi_threaded_message_loop)
     message_loop.reset(new MainMessageLoopMultithreadedWin);
   else if (settings.external_message_pump)