Revert of Revert of Referrer Policy: Update SanitizeForRequest with new default behavior.

content/public/common/referrer.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_PUBLIC_COMMON_REFERRER_H_
 #define CONTENT_PUBLIC_COMMON_REFERRER_H_
 
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "content/common/content_export.h"
+#include "content/public/common/content_switches.h"
 #include "third_party/WebKit/public/platform/WebReferrerPolicy.h"
 #include "url/gurl.h"
 
 namespace content {
 
 // This struct holds a referrer URL, as well as the referrer policy to be
 // applied to this URL. When passing around referrers that will eventually end
 // up being used for URL requests, always use this struct.
 struct CONTENT_EXPORT Referrer {
   Referrer(const GURL& url, blink::WebReferrerPolicy policy) : url(url),
                                                                 policy(policy) {
   }
   Referrer() : policy(blink::WebReferrerPolicyDefault) {
   }
 
   GURL url;
   blink::WebReferrerPolicy policy;
 
   static Referrer SanitizeForRequest(const GURL& request,
                                      const Referrer& referrer) {
     Referrer sanitized_referrer(referrer.url.GetAsReferrer(), referrer.policy);
 
     if (!request.SchemeIsHTTPOrHTTPS() ||
         !sanitized_referrer.url.SchemeIsHTTPOrHTTPS()) {
       sanitized_referrer.url = GURL();
       return sanitized_referrer;
     }
 
+    bool is_downgrade =
+        sanitized_referrer.url.SchemeIsSecure() && !request.SchemeIsSecure();
+
     switch (sanitized_referrer.policy) {
       case blink::WebReferrerPolicyDefault:
-        if (sanitized_referrer.url.SchemeIsSecure() &&
-            !request.SchemeIsSecure()) {
+        if (is_downgrade) {
           sanitized_referrer.url = GURL();
+        } else if (request.GetOrigin() != sanitized_referrer.url.GetOrigin() &&
+                   base::CommandLine::ForCurrentProcess()->HasSwitch(
+                       switches::kReducedReferrerGranularity)) {
+          sanitized_referrer.url = sanitized_referrer.url.GetOrigin();
         }
         break;
+      case blink::WebReferrerPolicyNoReferrerWhenDowngrade:
+        if (is_downgrade)
+          sanitized_referrer.url = GURL();
+        break;
       case blink::WebReferrerPolicyAlways:
         break;
       case blink::WebReferrerPolicyNever:
         sanitized_referrer.url = GURL();
         break;
       case blink::WebReferrerPolicyOrigin:
         sanitized_referrer.url = sanitized_referrer.url.GetOrigin();
         break;
       default:
         NOTREACHED();
         break;
     }
     return sanitized_referrer;
   }
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_REFERRER_H_