Anchor element's referrer attribute implementation for Referrer Policy

Source/core/html/HTMLAnchorElement.cpp

Index: Source/core/html/HTMLAnchorElement.cpp
diff --git a/Source/core/html/HTMLAnchorElement.cpp b/Source/core/html/HTMLAnchorElement.cpp
index 59c3697985672a09cd15bb8b49d6d8e2cf86a226..b4cbd8fba5dde58623250013e4749a29d73d64d5 100644
--- a/Source/core/html/HTMLAnchorElement.cpp
+++ b/Source/core/html/HTMLAnchorElement.cpp
@@ -358,8 +358,29 @@ void HTMLAnchorElement::handleClick(Event* event)
         request.setRequestContext(WebURLRequest::RequestContextHyperlink);
         FrameLoadRequest frameRequest(&document(), request, getAttribute(targetAttr));
         frameRequest.setTriggeringEvent(event);
-        if (hasRel(RelationNoReferrer))
-            frameRequest.setShouldSendReferrer(NeverSendReferrer);

[Mike West, 2015/05/20 07:56:41]

Is `ShouldSendReferrer` actually used after this patch? If not, please remove
it, along with its related methods.

[burnik, 2015/05/20 08:27:56]

I think it should be removed completely. Yesterday I was just to lazy to clean
up, but I've added myself a note.

The terms ShouldSendReferrer and MaybeSendReferrer sounds so non-deterministic
and clumsy anyway. My first taught was that it was boolean :D
 

[burnik, 2015/05/20 13:45:18]

Done.

+        // We keep it strict. If there is a rel attribute saying 'noreferrer', that takes precedence.
+        if (hasRel(RelationNoReferrer)) {
+            frameRequest.setReferrerPolicyForRequest(ReferrerPolicyNever);
+        } else if (hasAttribute(referrerAttr)) {
+            const AtomicString& referrerPolicy = fastGetAttribute(referrerAttr);
+            ReferrerPolicy referrerPolicyForRequest = ReferrerPolicyNoReferrerWhenDowngrade;

[Mike West, 2015/05/20 07:56:41]

Nit: You can pull this out of the `if`, set `referrerPolicyForRequest` in one of
the two branches, and then call `setReferrerPolicyForRequest` after the whole
thing once, rather than in both branches.

Nit: This should be `ReferrerPolicyDefault` when there's no attribute present,
or when the attribute is invalid.

[burnik, 2015/05/20 08:27:55]

Yes, I've seen it earlier, this initial approach was the worst possible
practice: code duplication, zero refactoring, etc. Just to get a feeling of how
things work together.

Done.

+
+            // FIXME: This string parsing should be implemented in one place and

[Mike West, 2015/05/20 07:56:41]

Nit: s/FIXME/TODO(burnik)/

[burnik, 2015/05/20 08:27:55]

Done.

+            // not duplicated from |blink::Document::processReferrerPolicy|.

[Mike West, 2015/05/20 07:56:41]

Perhaps you could extract this out to a method in
`platform/weborigin/ReferrerPolicy.h`?

You could extract the whole thing, actually, as you'll need similar code for
`<a>`, `<area>`, `<img>`, and `<iframe>`.

[burnik, 2015/05/20 08:27:55]

Yes, the FIXME(TODO) actually instructs me to do so. 
There should be two methods:

ReferrerPolicyFromString and ReferrerPoliyToString.

I believe the RP tests already implement those, so it should be a big win to
refactor this and have it in one place for reuse.

Note: <area> already inherits <a> so that part should already work.

+            if (equalIgnoringCase(referrerPolicy, "no-referrer") || equalIgnoringCase(referrerPolicy, "never"))
+                referrerPolicyForRequest = ReferrerPolicyNever;
+            else if (equalIgnoringCase(referrerPolicy, "unsafe-url") || equalIgnoringCase(referrerPolicy, "always"))
+                referrerPolicyForRequest = ReferrerPolicyAlways;
+            else if (equalIgnoringCase(referrerPolicy, "origin"))
+                referrerPolicyForRequest = ReferrerPolicyOrigin;
+            else if (equalIgnoringCase(referrerPolicy, "origin-when-cross-origin") || equalIgnoringCase(referrerPolicy, "origin-when-crossorigin"))
+                referrerPolicyForRequest = ReferrerPolicyOriginWhenCrossOrigin;
+            else if (equalIgnoringCase(referrerPolicy, "no-referrer-when-downgrade") || equalIgnoringCase(referrerPolicy, "default"))
+                referrerPolicyForRequest = ReferrerPolicyNoReferrerWhenDowngrade;
+
+            frameRequest.setReferrerPolicyForRequest(referrerPolicyForRequest);
+        }
+
         frame->loader().load(frameRequest);
     }
 }