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

content/public/common/referrer.h

Index: content/public/common/referrer.h
diff --git a/content/public/common/referrer.h b/content/public/common/referrer.h
index 122c5ead79096c2fb148d11206e8071f48671074..5a3b0118d4c5e108c5bf48fe3f7fa012c0a16f97 100644
--- a/content/public/common/referrer.h
+++ b/content/public/common/referrer.h
@@ -5,8 +5,10 @@
 #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"
 
@@ -35,12 +37,22 @@
       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;