Remove FrameDetached and FrameWillClose listeners from AutofillAgent.

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 101bdbaac650037f7f1fe506c428f3cb146e3572..b806b0f19ba92e7f064a21a8cc9f8f4398a48237 100644
--- a/content/public/renderer/render_frame_observer.h
+++ b/content/public/renderer/render_frame_observer.h
@@ -59,8 +59,15 @@ class CONTENT_EXPORT RenderFrameObserver : public IPC::Listener,
   virtual void WillSendSubmitEvent(const blink::WebFormElement& form) {}
   virtual void WillSubmitForm(const blink::WebFormElement& form) {}
 
+  // Called before FrameWillClose, when this frame has been detached from the
+  // view, but has not been closed yet. This *will* be called when parent frames
+  // are closing. NB: IPCs to the browser will fail silently by the time this
+  // notification is sent.
+  virtual void FrameDetached() {}
+
   // Called when the frame will soon be closed. This is the last opportunity to
-  // send messages to the host (e.g., for clean-up, shutdown, etc.).
+  // send messages to the host (e.g., for clean-up, shutdown, etc.). This is
+  // *not* called on child frames when parent frames are being closed.
   virtual void FrameWillClose() {}
 
   // Called when we receive a console message from Blink for which we requested