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 2c7bf68cbde14e102cffec87493b516ebc93755b..b67eab10e520e72bede3d8756b82ad3e0e5ed2ae 100644
--- a/content/browser/renderer_host/render_view_host_delegate.h
+++ b/content/browser/renderer_host/render_view_host_delegate.h
@@ -215,6 +215,11 @@ 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's main frame document element is ready. This happens when
   // the document has finished parsing.
   virtual void DocumentAvailableInMainFrame(RenderViewHost* render_view_host) {}