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/ceftests/devtools_message_unittest.cc

@@ -5,7 +5,8 @@
 #include <algorithm>
 #include <sstream>
 
-#include "include/base/cef_bind.h"
+#include "include/base/cef_callback.h"
+#include "include/base/cef_callback_helpers.h"
 #include "include/cef_callback.h"
 #include "include/cef_devtools_message_observer.h"
 #include "include/cef_parser.h"
@@ -281,7 +282,7 @@ class DevToolsMessageTestHandler : public TestHandler {
     // STEP 3: Page domain notifications are enabled. Now start a new
     // navigation (but do nothing on method result) and wait for the
     // "Page.frameNavigated" event.
-    ExecuteMethod("Page.navigate", params.str(), base::Bind(base::DoNothing),
+    ExecuteMethod("Page.navigate", params.str(), base::DoNothing(),
                   /*expected_result=*/"{\"frameId\":");
   }