Move middle-click autoscroll to synthetic fling.

third_party/WebKit/public/web/WebWidgetClient.h

 /*
  * Copyright (C) 2009 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 66 matching lines @@
   // Called immediately following the first compositor-driven (frame-generating)
   // layout that happened after an interesting document lifecyle change (see
   // WebMeaningfulLayout for details.)
   virtual void DidMeaningfulLayout(WebMeaningfulLayout) {}
 
   virtual void DidFirstLayoutAfterFinishedParsing() {}
 
   // Called when the cursor for the widget changes.
   virtual void DidChangeCursor(const WebCursorInfo&) {}
 
+  virtual void AutoscrollStart(const WebFloatPoint&) {}
+  virtual void AutoscrollFling(const WebFloatSize& velocity) {}
+  virtual void AutoscrollEnd() {}
+
   // Called when the widget should be closed.  WebWidget::close() should
   // be called asynchronously as a result of this notification.
   virtual void CloseWidgetSoon() {}
 
   // Called to show the widget according to the given policy.
   virtual void Show(WebNavigationPolicy) {}
 
   // Called to get/set the position of the widget's window in screen
   // coordinates. Note, the window includes any decorations such as borders,
   // scrollbars, URL bar, tab strip, etc. if they exist.
@@ skipping 85 matching lines @@
   virtual void StartDragging(WebReferrerPolicy,
                              const WebDragData&,
                              WebDragOperationsMask,
                              const WebImage& drag_image,
                              const WebPoint& drag_image_offset) {}
 };
 
 }  // namespace blink
 
 #endif