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

third_party/WebKit/Source/web/WebDataSourceImpl.h

Index: third_party/WebKit/Source/web/WebDataSourceImpl.h
diff --git a/third_party/WebKit/Source/web/WebDataSourceImpl.h b/third_party/WebKit/Source/web/WebDataSourceImpl.h
index bbc8efbdddf08445ea80e76d6ac7ea293c67bb31..a467887c8d9e4898898bf6de654734c176de08d2 100644
--- a/third_party/WebKit/Source/web/WebDataSourceImpl.h
+++ b/third_party/WebKit/Source/web/WebDataSourceImpl.h
@@ -37,6 +37,7 @@
 #include "platform/exported/WrappedResourceResponse.h"
 #include "platform/heap/Handle.h"
 #include "platform/weborigin/KURL.h"
+#include "public/platform/WebURL.h"
 #include "public/web/WebDataSource.h"
 #include "wtf/Vector.h"
 #include <memory>
@@ -48,13 +49,15 @@ class WebDataSourceImpl final : public DocumentLoader, public WebDataSource {
   static WebDataSourceImpl* create(LocalFrame*,
                                    const ResourceRequest&,
                                    const SubstituteData&,
-                                   ClientRedirectPolicy);
+                                   ClientRedirectPolicy,
+                                   Document* requestorDocument);
 
   static WebDataSourceImpl* fromDocumentLoader(DocumentLoader* loader) {
     return static_cast<WebDataSourceImpl*>(loader);
   }
 
   // WebDataSource methods:
+  WebURL requestorURL() const override;
   const WebURLRequest& originalRequest() const override;
   const WebURLRequest& request() const override;
   const WebURLResponse& response() const override;
@@ -82,7 +85,8 @@ class WebDataSourceImpl final : public DocumentLoader, public WebDataSource {
   WebDataSourceImpl(LocalFrame*,
                     const ResourceRequest&,
                     const SubstituteData&,
-                    ClientRedirectPolicy);
+                    ClientRedirectPolicy,
+                    Document* requestorDocument);
   ~WebDataSourceImpl() override;
   void detachFromFrame() override;
   String debugName() const override { return "WebDataSourceImpl"; }