Move LayoutObject::previousOffsetForBackwardDeletion() to editing.

third_party/WebKit/Source/core/layout/LayoutObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 1205 matching lines @@
     bool isFlexibleBoxIncludingDeprecated() const
     {
         return isFlexibleBox() || isDeprecatedFlexibleBox();
     }
 
     virtual bool isCombineText() const { return false; }
 
     virtual int caretMinOffset() const;
     virtual int caretMaxOffset() const;
 
-    virtual int previousOffsetForBackwardDeletion(int current) const;
-
-    // ImageResourceObserver override.
+    // ImageResourceClient override.
     void imageChanged(ImageResource*, const IntRect* = nullptr) final;
     bool willRenderImage() final;
     bool getImageAnimationPolicy(ImageAnimationPolicy&) final;
 
     // Sub-classes that have an associated image need to override this function
     // to get notified of any image change.
     virtual void imageChanged(WrappedImagePtr, const IntRect* = nullptr) { }
 
     void selectionStartEnd(int& spos, int& epos) const;
 
@@ skipping 927 matching lines @@
 void showTree(const blink::LayoutObject*);
 void showLineTree(const blink::LayoutObject*);
 void showLayoutTree(const blink::LayoutObject* object1);
 // We don't make object2 an optional parameter so that showLayoutTree
 // can be called from gdb easily.
 void showLayoutTree(const blink::LayoutObject* object1, const blink::LayoutObject* object2);
 
 #endif
 
 #endif // LayoutObject_h