SameSite: Correctly set requests' initiator for new tabs.

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

Index: third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
index 9166180f40520e80392a93c590b5a86b542d5cb8..f87dc9811204eb8450b87c5acdd93fe53411ba05 100644
--- a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
@@ -727,6 +727,25 @@ void FrameFetchContext::addCSPHeaderIfNecessary(Resource::Type type, FetchReques
         fetchRequest.mutableResourceRequest().addHTTPHeaderField("CSP", "active");
 }
 
+void FrameFetchContext::populateRequestorDataIfNecessary(ResourceRequest& request)
+{
+    if (!m_document)
+        return;
+
+    // Subresource requests inherit their requestor origin and first-party for
+    // cookies from |m_document| directly.
+    if (request.frameType() == WebURLRequest::FrameTypeNone) {
+        RefPtr<SecurityOrigin> documentSite = SecurityOrigin::create(m_document->url());
+        if (request.requestorOrigin()->isUnique() && !documentSite->isUnique())
+            request.setRequestorOrigin(documentSite);
+        if (request.firstPartyForCookies().isEmpty())
+            request.setFirstPartyForCookies(m_document->firstPartyForCookies());
+    }
+
+    // Top-level and nested frame types are taken care of in 'FrameLoadRequest()'.
+    // Auxiliary frame types in 'createWindow()' and 'FrameLoader::load'.
+}
+
 MHTMLArchive* FrameFetchContext::archive() const
 {
     ASSERT(!isMainFrame());