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/ssl_status_impl.h

@@ -15,6 +15,9 @@ class CefSSLStatusImpl : public CefSSLStatus {
  public:
   explicit CefSSLStatusImpl(const content::SSLStatus& value);
 
+  CefSSLStatusImpl(const CefSSLStatusImpl&) = delete;
+  CefSSLStatusImpl& operator=(const CefSSLStatusImpl&) = delete;
+
   // CefSSLStatus methods.
   bool IsSecureConnection() override;
   cef_cert_status_t GetCertStatus() override;
@@ -32,7 +35,6 @@ class CefSSLStatusImpl : public CefSSLStatus {
   CefRefPtr<CefX509Certificate> cef_certificate_;
 
   IMPLEMENT_REFCOUNTING(CefSSLStatusImpl);
-  DISALLOW_COPY_AND_ASSIGN(CefSSLStatusImpl);
 };
 
 #endif  // CEF_LIBCEF_BROWSER_SSL_STATUS_IMPL_H_