Notify the Blink client synchronously if the initial doc is accessed.

third_party/WebKit/public/web/WebFrameClient.h

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 139 matching lines @@
     // Returns a blame context for attributing work belonging to this frame.
     virtual BlameContext* frameBlameContext() { return nullptr; }
 
     // General notifications -----------------------------------------------
 
     // Indicates if creating a plugin without an associated renderer is supported.
     virtual bool canCreatePluginWithoutRenderer(const WebString& mimeType) { return false; }
 
     // Indicates that another page has accessed the DOM of the initial empty
     // document of a main frame. After this, it is no longer safe to show a
-    // pending navigation's URL, because a URL spoof is possible.
+    // pending navigation's URL, because a URL spoof is possible. The client
+    // must not call back into JavaScript during this notification.
     virtual void didAccessInitialDocument() { }
 
     // A child frame was created in this frame. This is called when the frame
     // is created and initialized. Takes the name of the new frame, the parent
     // frame and returns a new WebFrame. The WebFrame is considered in-use
     // until frameDetached() is called on it.
     // Note: If you override this, you should almost certainly be overriding
     // frameDetached().
     virtual WebFrame* createChildFrame(WebLocalFrame* parent, WebTreeScopeType, const WebString& name, const WebString& uniqueName, WebSandboxFlags sandboxFlags, const WebFrameOwnerProperties&) { return nullptr; }
 
@@ skipping 550 matching lines @@
         return WebPageVisibilityStateVisible;
     }
 
 protected:
     virtual ~WebFrameClient() { }
 };
 
 } // namespace blink
 
 #endif