Apply meta tag referrer policy for preloaded requests

Source/platform/weborigin/SecurityPolicy.cpp

 /*
  * Copyright (C) 2011 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 192 matching lines @@
     if (list->isEmpty())
         map.remove(it);
 }
 
 void SecurityPolicy::resetOriginAccessWhitelists()
 {
     ASSERT(isMainThread());
     originAccessMap().clear();
 }
 
+bool SecurityPolicy::referrerPolicyFromString(const String& policy, ReferrerPolicy* result)
+{
+    ASSERT(!policy.isNull());
+
+    if (equalIgnoringCase(policy, "no-referrer") || equalIgnoringCase(policy, "never")) {
+        *result = ReferrerPolicyNever;
+        return true;
+    }
+    if (equalIgnoringCase(policy, "unsafe-url") || equalIgnoringCase(policy, "always")) {
+        *result = ReferrerPolicyAlways;
+        return true;
+    }
+    if (equalIgnoringCase(policy, "origin")) {
+        *result = ReferrerPolicyOrigin;
+        return true;
+    }
+    if (equalIgnoringCase(policy, "origin-when-cross-origin") || equalIgnoringCase(policy, "origin-when-crossorigin")) {
+        *result = ReferrerPolicyOriginWhenCrossOrigin;
+        return true;
+    }
+    if (equalIgnoringCase(policy, "no-referrer-when-downgrade") || equalIgnoringCase(policy, "default")) {
+        *result = ReferrerPolicyNoReferrerWhenDowngrade;
+        return true;
+    }
+    return false;
+}
+
 } // namespace blink