Add a check that we don't send a secure referrer to an insecure URL

net/url_request/url_request.cc

Index: net/url_request/url_request.cc
diff --git a/net/url_request/url_request.cc b/net/url_request/url_request.cc
index 6b0124730d5011fec92ddbf733be8f24f2db6ffa..437d8c7325b0865edeff0dc8e09c66803f8fcf83 100644
--- a/net/url_request/url_request.cc
+++ b/net/url_request/url_request.cc
@@ -684,6 +684,13 @@ void URLRequest::StartJob(URLRequestJob* job) {
 
   response_info_.was_cached = false;
 
+  // If the referrer is secure, but the requested URL is not, the referrer
+  // policy should be something non-default. If you hit this, please file a
+  // bug.
+  CHECK(!(GURL(referrer_).SchemeIsSecure() && !url().SchemeIsSecure()) ||
+        referrer_policy_ !=
+            CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE);

[mef, 2013/12/16 16:39:01]

I'd keep it as DCHECK to avoid non-critical crashes.

[jochen (gone - plz use gerrit), 2013/12/16 19:25:51]

IMO a DCHECK is almost pointless. And it is a  critical error if this happens in
the wild.

+
   // Don't allow errors to be sent from within Start().
   // TODO(brettw) this may cause NotifyDone to be sent synchronously,
   // we probably don't want this: they should be sent asynchronously so