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.h

@@ -6,7 +6,8 @@
 #define CEF_TESTS_CEFCLIENT_BROWSER_BROWSER_WINDOW_H_
 #pragma once
 
-#include "include/base/cef_scoped_ptr.h"
+#include <memory>
+
 #include "include/cef_browser.h"
 #include "tests/cefclient/browser/client_handler.h"
 #include "tests/cefclient/browser/client_types.h"
@@ -110,8 +111,8 @@ class BrowserWindow : public ClientHandler::Delegate {
   bool IsClosing() const;
 
  protected:
-  // Allow deletion via scoped_ptr only.
-  friend struct base::DefaultDeleter<BrowserWindow>;
+  // Allow deletion via std::unique_ptr only.
+  friend std::default_delete<BrowserWindow>;
 
   // Constructor may be called on any thread.
   // |delegate| must outlive this object.