[All-In-One] Introduce BackspaceStateMachine

third_party/WebKit/Source/core/layout/LayoutText.cpp

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 1656 matching lines @@
         return current - 1;
 
     long result = iterator->preceding(current);
     if (result == TextBreakDone)
         result = current - 1;
 
 
     return result;
 }
 
-int LayoutText::previousOffsetForBackwardDeletion(int current) const
-{
-    // Delete by one code point. Ideally we should delete grapheme where that
-    // makes sense. https://crbug.com/587241
-    if (U16_IS_TRAIL(m_text[--current]))
-        --current;
-    if (current < 0)
-        current = 0;
-    return current;
-}
-
 int LayoutText::nextOffset(int current) const
 {
     if (m_text.is8Bit())
         return current + 1;
 
     StringImpl* textImpl = m_text.impl();
     TextBreakIterator* iterator = cursorMovementIterator(textImpl->characters16(), textImpl->length());
     if (!iterator)
         return current + 1;
 
@@ skipping 53 matching lines @@
     for (InlineTextBox* box = firstTextBox(); box; box = box->nextTextBox()) {
         paintInvalidationContainer.invalidateDisplayItemClientOnBacking(*box, invalidationReason);
         if (box->truncation() != cNoTruncation) {
             if (EllipsisBox* ellipsisBox = box->root().ellipsisBox())
                 paintInvalidationContainer.invalidateDisplayItemClientOnBacking(*ellipsisBox, invalidationReason);
         }
     }
 }
 
 } // namespace blink