Make leadingWhitespacePosition() to respect "white-space" CSS property

third_party/WebKit/Source/core/editing/EditingUtilities.h

 /*
  * Copyright (C) 2004, 2006, 2008 Apple 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:
  * 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
  *    notice, this list of conditions and the following disclaimer in the
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 // FIXME: isRichlyEditablePosition should also take EUpdateStyle.
 CORE_EXPORT bool isEditablePosition(const Position&, EditableType = ContentIsEditable, EUpdateStyle = UpdateStyle);
 bool isEditablePosition(const PositionInFlatTree&, EditableType = ContentIsEditable, EUpdateStyle = UpdateStyle);
 bool isRichlyEditablePosition(const Position&, EditableType = ContentIsEditable);
 bool lineBreakExistsAtPosition(const Position&);
 bool isAtUnsplittableElement(const Position&);
 
 // miscellaneous functions on Position
 
 enum WhitespacePositionOption { NotConsiderNonCollapsibleWhitespace, ConsiderNonCollapsibleWhitespace };
+
+// |leadingWhitespacePosition(position)| returns a previous position of
+// |position| if it is at collapsible whitespace, otherwise it returns null
+// position. When it is called with |NotConsiderNonCollapsibleWhitespace| and
+// a previous position in a element which has CSS property "white-space:pre",
+// or its variant, |leadingWhitespacePosition()| returns null position.
+// TODO(yosin) We should rename |leadingWhitespacePosition()| to
+// |leadingCollapsibleWhitespacePosition()| as this function really returns.
 Position leadingWhitespacePosition(const Position&, TextAffinity, WhitespacePositionOption = NotConsiderNonCollapsibleWhitespace);
 Position trailingWhitespacePosition(const Position&, TextAffinity, WhitespacePositionOption = NotConsiderNonCollapsibleWhitespace);
 unsigned numEnclosingMailBlockquotes(const Position&);
 void updatePositionForNodeRemoval(Position&, Node&);
 
 // -------------------------------------------------------------------------
 // VisiblePosition
 // -------------------------------------------------------------------------
 
 // Functions returning VisiblePosition
@@ skipping 83 matching lines @@
     // FIXME: this is required until 6853027 is fixed and text checking can do this for us.
     return character == '\'' || character == rightSingleQuotationMarkCharacter || character == hebrewPunctuationGershayimCharacter;
 }
 
 String stringWithRebalancedWhitespace(const String&, bool startIsStartOfParagraph, bool endIsEndOfParagraph);
 const String& nonBreakingSpaceString();
 
 } // namespace blink
 
 #endif