Anchor element's referrer attribute implementation for Referrer Policy

Source/platform/weborigin/ReferrerPolicy.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 14 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */
 
 #ifndef ReferrerPolicy_h
 #define ReferrerPolicy_h
 
+#include "wtf/text/WTFString.h"
+
 namespace blink {
 
 enum ReferrerPolicy {
     // https://w3c.github.io/webappsec/specs/referrer-policy/#referrer-policy-state-unsafe-url
     ReferrerPolicyAlways,
     // The default policy, if no policy is explicitly set by the page.
     ReferrerPolicyDefault,
     // https://w3c.github.io/webappsec/specs/referrer-policy/#referrer-policy-state-no-referrer-when-downgrade
     ReferrerPolicyNoReferrerWhenDowngrade,
     // https://w3c.github.io/webappsec/specs/referrer-policy/#referrer-policy-state-no-referrer
     ReferrerPolicyNever,
     // https://w3c.github.io/webappsec/specs/referrer-policy/#referrer-policy-state-origin
     ReferrerPolicyOrigin,
     // https://w3c.github.io/webappsec/specs/referrer-policy/#referrer-policy-state-origin-when-cross-origin
-    ReferrerPolicyOriginWhenCrossOrigin,
+    ReferrerPolicyOriginWhenCrossOrigin
 };
 
+bool ParseReferrerPolicy(const WTF::String&, ReferrerPolicy*);
+
+WTF::String ReferrerPolicyToString(ReferrerPolicy);
+
 }
 
 #endif // ReferrerPolicy_h