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 06ef91fc9f7dbf98bf00774aa407e825ff83208f..2847f135ec87edbbd97c9cc3663d4de843377f13 100644
--- a/public/web/WebRemoteFrameClient.h
+++ b/public/web/WebRemoteFrameClient.h
@@ -20,6 +20,10 @@ public:
         WebRemoteFrame* targetFrame,
         WebSecurityOrigin targetOrigin,
         WebDOMMessageEvent) = 0;
+
+    // A remote frame was asked to start a navigation.
+    virtual void navigate(WebRemoteFrame* frame, const WebURLRequest& request,
+        bool shouldReplaceCurrentEntry) { }
 };
 
 } // namespace blink