blimp: Update page load status update indicator to use first paint.

content/public/browser/web_contents_observer.h

Index: content/public/browser/web_contents_observer.h
diff --git a/content/public/browser/web_contents_observer.h b/content/public/browser/web_contents_observer.h
index 1b8f1996095c2a5fa5fac80b1fe1534f5c14b98e..5f52021c2e69e93467c67293c0ff2078960233b9 100644
--- a/content/public/browser/web_contents_observer.h
+++ b/content/public/browser/web_contents_observer.h
@@ -318,6 +318,10 @@ class CONTENT_EXPORT WebContentsObserver : public IPC::Listener,
   // paint after a non-empty layout.
   virtual void DidFirstVisuallyNonEmptyPaint() {}
 
+  // This method is invoked when the main frame in the renderer process performs
+  // the first paint after a navigation.
+  virtual void DidFirstPaintAfterLoad(RenderWidgetHost* render_widget_host) {}
+
   // When WebContents::Stop() is called, the WebContents stops loading and then
   // invokes this method. If there are ongoing navigations, their respective
   // failure methods will also be invoked.