Make printing work better with OOPIF.

content/public/renderer/render_frame_observer.h

Index: content/public/renderer/render_frame_observer.h
diff --git a/content/public/renderer/render_frame_observer.h b/content/public/renderer/render_frame_observer.h
index ea667d4a8125715a4cf577484ad235720e0848ad..7a51d36e5b0f117de7e4ddf9bcf8495fa97ccb5c 100644
--- a/content/public/renderer/render_frame_observer.h
+++ b/content/public/renderer/render_frame_observer.h
@@ -122,6 +122,11 @@ class CONTENT_EXPORT RenderFrameObserver : public IPC::Listener,
   // Called when accessibility is enabled or disabled.
   virtual void AccessibilityModeChanged() {}
 
+  // For printing.
+  virtual void ScriptedPrint(bool user_initiated) {}
+  virtual void DidStartLoading() {}

[nasko, 2016/10/27 20:26:26]

Let's not add this, as Start/Stop Loading is global for the full page, which
isn't per frame.
DidStartLoading can be replaced by DidStartProvisionalLoad.
DidStopLoading can be replaced by combo of DidFailProvisionalLoad for failure
case and DidFinishLoad for the success case.

[Lei Zhang, 2016/10/28 23:27:10]

Done.

+  virtual void DidStopLoading() {}
+
   // IPC::Listener implementation.
   bool OnMessageReceived(const IPC::Message& message) override;