Add basic Referrer-Policy support for Documents

third_party/WebKit/Source/core/loader/FrameLoader.cpp

Index: third_party/WebKit/Source/core/loader/FrameLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameLoader.cpp b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
index 98043161ced3d6f7e13f09d89c9b864899bb2490..7a7ef0287647b31e51be1d441fc14782ce0f089e 100644
--- a/third_party/WebKit/Source/core/loader/FrameLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
@@ -85,6 +85,7 @@
 #include "core/xml/parser/XMLDocumentParser.h"
 #include "platform/Logging.h"
 #include "platform/PluginScriptForbiddenScope.h"
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/ScriptForbiddenScope.h"
 #include "platform/TraceEvent.h"
 #include "platform/UserGestureIndicator.h"
@@ -514,6 +515,16 @@ void FrameLoader::didBeginDocument()
         OriginTrialContext::addTokensFromHeader(m_frame->document(), m_documentLoader->response().httpHeaderField(HTTPNames::Origin_Trial));
     }
 
+    if (m_documentLoader && RuntimeEnabledFeatures::referrerPolicyHeaderEnabled()) {
+        String referrerPolicyHeader = m_documentLoader->response().httpHeaderField(HTTPNames::Referrer_Policy);
+        if (!referrerPolicyHeader.isNull()) {
+            ReferrerPolicy referrerPolicy = parseReferrerPolicyHeader(referrerPolicyHeader);

[Mike West, 2016/06/21 07:40:03]

Could you call `Document::processReferrerPolicy(referrerPolicyHeader)` instead,
and either inline the new parsing code there (or in
`SecurityPolicy::referrerPolicyFromString(...)`, I suppose?), making the header
behave exactly the same way as `<meta>`? This would have the impact of allowing
comma-separated tokens in the `<meta>` content, but I think I'd prefer that to
having two separate code paths.

[estark, 2016/06/21 17:41:33]

Hmm. If I put the new parsing code in Document::processReferrerPolicy(), then I
can't easily reuse it for processing headers delivered on Worker scripts. If I
put it in SecurityPolicy::referrerPolicyFromString(), then that means
comma-separated values will also be allowed for the 'referrerpolicy' attribute,
which seems weird to me.

I could move Document::processReferrerPolicy() to be a method on
ExecutionContext instead of Document and do the new parsing there, so that I can
call it for both Documents and Workers. WDYT of that plan?

[Mike West, 2016/06/22 18:57:04]

I trust your judgement. I think it's probably reasonable to just accept `a, b,
c` in `<meta>` and send them through the same processing internally, but if
you'd prefer not to do that, more power to you.

LGTM either way.

+            if (referrerPolicy != ReferrerPolicyDefault) {
+                m_frame->document()->setReferrerPolicy(referrerPolicy);
+            }
+        }
+    }
+
     client()->didCreateNewDocument();
 }