Implement referrerpolicy attribute for img elements

Source/core/html/parser/HTMLPreloadScanner.cpp

Index: Source/core/html/parser/HTMLPreloadScanner.cpp
diff --git a/Source/core/html/parser/HTMLPreloadScanner.cpp b/Source/core/html/parser/HTMLPreloadScanner.cpp
index 055e811b23f9025c037f00a0e4963680a3e4e484..ab469e57714fcb5c14deb700462d2d9a6b017e80 100644
--- a/Source/core/html/parser/HTMLPreloadScanner.cpp
+++ b/Source/core/html/parser/HTMLPreloadScanner.cpp
@@ -123,6 +123,7 @@ public:
         , m_defer(FetchRequest::NoDefer)
         , m_allowCredentials(DoNotAllowStoredCredentials)
         , m_mediaValues(mediaValues)
+        , m_referrerPolicy(ReferrerPolicyDefault)
     {
         ASSERT(m_mediaValues->isCached());
         if (match(m_tagImpl, imgTag)
@@ -174,7 +175,7 @@ public:
         }
     }
 
-    PassOwnPtr<PreloadRequest> createPreloadRequest(const KURL& predictedBaseURL, const SegmentedString& source, const ClientHintsPreferences& clientHintsPreferences, const PictureData& pictureData, const ReferrerPolicy referrerPolicy)
+    PassOwnPtr<PreloadRequest> createPreloadRequest(const KURL& predictedBaseURL, const SegmentedString& source, const ClientHintsPreferences& clientHintsPreferences, const PictureData& pictureData, const ReferrerPolicy documentReferrerPolicy)
     {
         PreloadRequest::RequestType requestType = PreloadRequest::RequestTypePreload;
         if (shouldPreconnect())
@@ -195,6 +196,9 @@ public:
             resourceWidth.isSet = true;
         }
 
+        // The element's 'referrerpolicy' attribute (if present) takes
+        // precedence over the document's referrer policy.
+        ReferrerPolicy referrerPolicy = m_referrerPolicy != ReferrerPolicyDefault ? m_referrerPolicy : documentReferrerPolicy;
         OwnPtr<PreloadRequest> request = PreloadRequest::create(initiatorFor(m_tagImpl), position, m_urlToLoad, predictedBaseURL, resourceType(), referrerPolicy, resourceWidth, clientHintsPreferences, requestType);
         if (isCORSEnabled())
             request->setCrossOriginEnabled(allowStoredCredentials());
@@ -237,6 +241,13 @@ private:
                 m_srcsetImageCandidate = bestFitSourceForSrcsetAttribute(m_mediaValues->devicePixelRatio(), m_sourceSize, m_srcsetAttributeValue);
                 setUrlToLoad(bestFitSourceForImageAttributes(m_mediaValues->devicePixelRatio(), m_sourceSize, m_imgSrcUrl, m_srcsetImageCandidate), AllowURLReplacement);
             }
+        } else if (match(attributeName, referrerpolicyAttr) && !attributeValue.isNull()) {
+            ReferrerPolicy parsedPolicy;
+            if (SecurityPolicy::referrerPolicyFromString(attributeValue, &parsedPolicy)) {
+                m_referrerPolicy = parsedPolicy;
+            } else {
+                m_referrerPolicy = ReferrerPolicyDefault;
+            }

[Yoav Weiss, 2015/08/18 21:09:21]

I believe we can replace the last 6 lines with
`SecurityPolicy::referrerPolicyFromString(attributeValue, &m_referrerPolicy)`
(since referrerPolicyFromString doesn't have any side effects on the input
referrerPolicy pointer in case it returns false)

[estark, 2015/08/19 02:53:22]

Done.

         }
     }
 
@@ -411,6 +422,7 @@ private:
     FetchRequest::DeferOption m_defer;
     StoredCredentials m_allowCredentials;
     RefPtrWillBeMember<MediaValues> m_mediaValues;
+    ReferrerPolicy m_referrerPolicy;
 };
 
 TokenPreloadScanner::TokenPreloadScanner(const KURL& documentURL, PassOwnPtr<CachedDocumentParameters> documentParameters)
@@ -593,6 +605,7 @@ void TokenPreloadScanner::scanCommon(const Token& token, const SegmentedString&
         scanner.processAttributes(token.attributes());
         if (m_inPicture)
             scanner.handlePictureSourceURL(m_pictureData);
+

[Yoav Weiss, 2015/08/18 21:09:21]

Nit: spurious new line

[estark, 2015/08/19 02:53:22]

Done.

         OwnPtr<PreloadRequest> request = scanner.createPreloadRequest(m_predictedBaseElementURL, source, m_clientHintsPreferences, m_pictureData, m_documentParameters->referrerPolicy);
         if (request)
             requests.append(request.release());