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..4441b26c8e5efa0ed8a070dbd63392d9048734af 100644
--- a/net/url_request/url_request.h
+++ b/net/url_request/url_request.h
@@ -94,14 +94,21 @@ 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 is
+  // redirected cross-origin, but does not degrade to an insecure connection,
+  // the referrer will be delivered with reduced granularity (e.g. an origin
+  // rather than a full URL).

[mmenke, 2014/11/19 16:29:03]

I don't think your last paragraph makes it sufficiently clear that it's applied
to HTTP->HTTP and HTTP->HTTPS redirects, in addition to HTTPS->HTTPS ones.

[Mike West, 2014/11/20 10:45:30]

Attempted to clarify. WDYT?

   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,
   };
 
@@ -294,6 +301,11 @@ class NET_EXPORT URLRequest : NON_EXPORTED_BASE(public base::NonThreadSafe),
   const std::string& referrer() const { return referrer_; }
   // Referrer is sanitized to remove URL fragment, user name and password.
   void SetReferrer(const std::string& referrer);
+  // Returns true if the referrer is invalid for this request, given its
+  // referrer policy. This could mean that a secure referrer is set for a
+  // request which should have dropped it, or that a full referrer url is set
+  // for a request which should have trimmed it to an origin.
+  bool IsReferrerInvalid() const;
 
   // The referrer policy to apply when updating the referrer during redirects.
   // The referrer policy may only be changed before Start() is called.