Remove DISALLOW_ macro from libcef/ (see issue #3234)

Also perform related C++ cleanup:
- Use =default instead of {} for default implementations of
  constructors/destructors.
- Replace typedef with using.

libcef/browser/printing/constrained_window_views_client.cc

@@ -5,7 +5,6 @@
 #include "libcef/browser/printing/constrained_window_views_client.h"
 
 #include "base/logging.h"
-#include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/notreached.h"
 #include "chrome/browser/platform_util.h"
@@ -18,6 +17,12 @@ class CefConstrainedWindowViewsClient
     : public constrained_window::ConstrainedWindowViewsClient {
  public:
   CefConstrainedWindowViewsClient() {}
+
+  CefConstrainedWindowViewsClient(const CefConstrainedWindowViewsClient&) =
+      delete;
+  CefConstrainedWindowViewsClient& operator=(
+      const CefConstrainedWindowViewsClient&) = delete;
+
   ~CefConstrainedWindowViewsClient() override {}
 
  private:
@@ -31,8 +36,6 @@ class CefConstrainedWindowViewsClient
     NOTREACHED();
     return gfx::NativeView();
   }
-
-  DISALLOW_COPY_AND_ASSIGN(CefConstrainedWindowViewsClient);
 };
 
 }  // namespace