Expand TextCheckingParagraph::OffsetTo() into SelectionController::MarkAndReplaceFor()

third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 586 matching lines @@
     // "editing/spelling/spellcheck-async-mutation.html" reaches here.
     return;
   }
 
   TextCheckingParagraph paragraph(checking_range, checking_range);
 
   // TODO(xiaochengh): The following comment does not match the current behavior
   // and should be rewritten.
   // Expand the range to encompass entire paragraphs, since text checking needs
   // that much context.
-  int selection_offset = 0;
   int ambiguous_boundary_offset = -1;
 
   if (GetFrame().Selection().ComputeVisibleSelectionInDOMTree().IsCaret()) {
     // TODO(xiaochengh): The following comment does not match the current
     // behavior and should be rewritten.
     // Attempt to save the caret position so we can restore it later if needed
     const Position& caret_position =
         GetFrame().Selection().ComputeVisibleSelectionInDOMTree().end();
-    selection_offset = paragraph.OffsetTo(caret_position);
+    const Position& paragraph_start = checking_range.StartPosition();
+    const int selection_offset =
+        paragraph_start < caret_position
+            ? TextIterator::RangeLength(paragraph_start, caret_position)
+            : 0;
     if (selection_offset > 0 &&
         static_cast<unsigned>(selection_offset) <=
             paragraph.GetText().length() &&
         IsAmbiguousBoundaryCharacter(
             paragraph.TextCharAt(selection_offset - 1))) {
       ambiguous_boundary_offset = selection_offset - 1;
     }
   }
 
   const int spelling_range_end_offset = paragraph.CheckingEnd();
@@ skipping 605 matching lines @@
       if (!input.IsFocusedElementInDocument())
         return false;
     }
   }
   HTMLElement* element =
       Traversal<HTMLElement>::FirstAncestorOrSelf(*position.AnchorNode());
   return element && element->IsSpellCheckingEnabled();
 }
 
 }  // namespace blink