Expose the initiating origin/URL of a navigation in the Blink public API

third_party/WebKit/Source/web/WebDataSourceImpl.cpp

Index: third_party/WebKit/Source/web/WebDataSourceImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebDataSourceImpl.cpp b/third_party/WebKit/Source/web/WebDataSourceImpl.cpp
index 87d7436594aaa6c661bb7cdb376afe18dc1db45a..1c610593947b1464897666c9f4457a9963ca7691 100644
--- a/third_party/WebKit/Source/web/WebDataSourceImpl.cpp
+++ b/third_party/WebKit/Source/web/WebDataSourceImpl.cpp
@@ -44,8 +44,14 @@ WebDataSourceImpl* WebDataSourceImpl::create(
     LocalFrame* frame,
     const ResourceRequest& request,
     const SubstituteData& data,
-    ClientRedirectPolicy clientRedirectPolicy) {
-  return new WebDataSourceImpl(frame, request, data, clientRedirectPolicy);
+    ClientRedirectPolicy clientRedirectPolicy,
+    Document* requestorDocument) {
+  return new WebDataSourceImpl(frame, request, data, clientRedirectPolicy,
+                               requestorDocument);
+}
+
+WebURL WebDataSourceImpl::requestorURL() const {
+  return requestorDocument() ? WebURL(requestorDocument()->url()) : WebURL();
 }
 
 const WebURLRequest& WebDataSourceImpl::originalRequest() const {
@@ -139,8 +145,13 @@ WebNavigationType WebDataSourceImpl::toWebNavigationType(NavigationType type) {
 WebDataSourceImpl::WebDataSourceImpl(LocalFrame* frame,
                                      const ResourceRequest& request,
                                      const SubstituteData& data,
-                                     ClientRedirectPolicy clientRedirectPolicy)
-    : DocumentLoader(frame, request, data, clientRedirectPolicy),
+                                     ClientRedirectPolicy clientRedirectPolicy,
+                                     Document* requestorDocument)
+    : DocumentLoader(frame,
+                     request,
+                     data,
+                     clientRedirectPolicy,
+                     requestorDocument),
       m_originalRequestWrapper(DocumentLoader::originalRequest()),
       m_requestWrapper(DocumentLoader::request()),
       m_responseWrapper(DocumentLoader::response()) {}