Revert of Revert of Make start/stop loading notifications per-frame

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 149 matching lines @@
 
     // The client may choose to alter the navigation policy.  Otherwise,
     // defaultPolicy should just be returned.
     virtual WebNavigationPolicy decidePolicyForNavigation(
         WebLocalFrame*, WebDataSource::ExtraData*, const WebURLRequest&, WebNavigationType,
         WebNavigationPolicy defaultPolicy, bool isRedirect) { return defaultPolicy; }
 
 
     // Navigational notifications ------------------------------------------
 
+    // These notifications bracket any loading that occurs in the WebFrame.
+    virtual void didStartLoading(bool toDifferentDocument) { }
+    virtual void didStopLoading() { }
+
+    // Notification that some progress was made loading the current frame.
+    // loadProgress is a value between 0 (nothing loaded) and 1.0 (frame fully
+    // loaded).
+    virtual void didChangeLoadProgress(double loadProgress) { }
+
     // A form submission has been requested, but the page's submit event handler
     // hasn't yet had a chance to run (and possibly alter/interrupt the submit.)
     virtual void willSendSubmitEvent(WebLocalFrame*, const WebFormElement&) { }
 
     // A form submission is about to occur.
     virtual void willSubmitForm(WebLocalFrame*, const WebFormElement&) { }
 
     // A datasource has been created for a new navigation.  The given
     // datasource will become the provisional datasource for the frame.
     virtual void didCreateDataSource(WebLocalFrame*, WebDataSource*) { }
@@ skipping 223 matching lines @@
     // Send initial drawing parameters to a child frame that is being rendered out of process.
     virtual void initializeChildFrame(const WebRect& frameRect, float scaleFactor) { }
 
 protected:
     ~WebFrameClient() { }
 };
 
 } // namespace blink
 
 #endif