Plumbing toward transitioning remote frame back to a local frame.

public/web/WebRemoteFrameClient.h

Index: public/web/WebRemoteFrameClient.h
diff --git a/public/web/WebRemoteFrameClient.h b/public/web/WebRemoteFrameClient.h
index 9601a6376953248366a3838d900c77adab0588ab..6bbd42d67daf0b4ef7d3447fcba372bc03f9aa7e 100644
--- a/public/web/WebRemoteFrameClient.h
+++ b/public/web/WebRemoteFrameClient.h
@@ -30,6 +30,9 @@ public:
     virtual void initializeChildFrame(
         const WebRect& frameRect,
         float scaleFactor) { }
+
+    // A remote frame was asked to start a navigation.
+    virtual void navigate(const WebURLRequest& request, bool shouldReplaceCurrentEntry) { }
 };
 
 } // namespace blink