Allow showing pending URL for new tab navigations, but only if safe.

content/browser/renderer_host/render_view_host_delegate.h

Index: content/browser/renderer_host/render_view_host_delegate.h
diff --git a/content/browser/renderer_host/render_view_host_delegate.h b/content/browser/renderer_host/render_view_host_delegate.h
index 5ee731405cb64f4bb04d6da752622b1b1e294133..a32c8d4a9119e2929ff93fce67b22ec55bf1d567 100644
--- a/content/browser/renderer_host/render_view_host_delegate.h
+++ b/content/browser/renderer_host/render_view_host_delegate.h
@@ -219,6 +219,11 @@ class CONTENT_EXPORT RenderViewHostDelegate {
   // the window.
   virtual void DidDisownOpener(RenderViewHost* rvh) {}
 
+  // Another page accessed the initial empty document of this RenderView,
+  // which means it is no longer safe to display a pending URL without
+  // risking a URL spoof.
+  virtual void DidAccessInitialDocument() {}
+
   // The RenderView has changed its frame hierarchy, so we need to update all
   // other renderers interested in this event.
   virtual void DidUpdateFrameTree(RenderViewHost* rvh) {}