Referrer Policy: Add new policies to URLRequest.

net/url_request/url_request.h

Index: net/url_request/url_request.h
diff --git a/net/url_request/url_request.h b/net/url_request/url_request.h
index 61174192c89e6eb1cd5faa54b39f5871e2ea014b..af972bd2df7c15500b429c99b22e16b28bd55f9e 100644
--- a/net/url_request/url_request.h
+++ b/net/url_request/url_request.h
@@ -94,14 +94,22 @@ class NET_EXPORT URLRequest : NON_EXPORTED_BASE(public base::NonThreadSafe),
   // referrer header might be cleared, if the protocol changes from HTTPS to
   // HTTP. This is the default behavior of URLRequest, corresponding to
   // CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE. Alternatively, the
-  // referrer policy can be set to never change the referrer header. This
-  // behavior corresponds to NEVER_CLEAR_REFERRER. Embedders will want to use
-  // NEVER_CLEAR_REFERRER when implementing the meta-referrer support
-  // (http://wiki.whatwg.org/wiki/Meta_referrer) and sending requests with a
-  // non-default referrer policy. Only the default referrer policy requires
-  // the referrer to be cleared on transitions from HTTPS to HTTP.
+  // referrer policy can be set to strip the referrer down to an origin upon
+  // cross-origin navigation (ORIGIN_ONLY_ON_TRANSITION_CROSS_ORIGIN), or
+  // never change the referrer header (NEVER_CLEAR_REFERRER). Embedders will
+  // want to use these options when implementing referrer policy support
+  // (https://w3c.github.io/webappsec/specs/referrer-policy/).
+  //
+  // REDUCE_REFERRER_GRANULARITY_ON_TRANSITION_CROSS_ORIGIN is a slight variant
+  // on CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE: If the request
+  // downgrades from HTTPS to HTTP, the referrer will be cleared. If the request
+  // transitions cross-origin (but does not downgrade), the referrer's
+  // granularity will be reduced (currently stripped down to an origin rather
+  // than a full URL). Same-origin requests will send the full referrer.
   enum ReferrerPolicy {
     CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE,
+    REDUCE_REFERRER_GRANULARITY_ON_TRANSITION_CROSS_ORIGIN,
+    ORIGIN_ONLY_ON_TRANSITION_CROSS_ORIGIN,
     NEVER_CLEAR_REFERRER,
   };