RenderTextHarfBuzz: Allow mid-glyph cursors in multi-grapheme clusters

base/i18n/break_iterator.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_I18N_BREAK_ITERATOR_H_
 #define BASE_I18N_BREAK_ITERATOR_H_
 
 #include "base/basictypes.h"
 #include "base/i18n/base_i18n_export.h"
 #include "base/strings/string16.h"
@@ skipping 88 matching lines @@
   // whitespace or punctuation.)  Under BREAK_LINE and BREAK_NEWLINE modes,
   // this distinction doesn't apply and it always returns false.
   bool IsWord() const;
 
   // Under BREAK_WORD mode, returns true if |position| is at the end of word or
   // at the start of word. It always returns false under BREAK_LINE and
   // BREAK_NEWLINE modes.
   bool IsEndOfWord(size_t position) const;
   bool IsStartOfWord(size_t position) const;
 
+  // Under BREAK_CHARACTER mode, returns whether |position| is a Unicode
+  // grapheme boundary.
+  bool IsGraphemeBoundary(size_t position) const;
+
   // Returns the string between prev() and pos().
   // Advance() must have been called successfully at least once for pos() to
   // have advanced to somewhere useful.
   string16 GetString() const;
 
   // Returns the value of pos() returned before Advance() was last called.
   size_t prev() const { return prev_; }
 
   // Returns the current break position within the string,
   // or BreakIterator::npos when done.
@@ skipping 18 matching lines @@
   // Previous and current iterator positions.
   size_t prev_, pos_;
 
   DISALLOW_COPY_AND_ASSIGN(BreakIterator);
 };
 
 }  // namespace i18n
 }  // namespace base
 
 #endif  // BASE_I18N_BREAK_ITERATOR_H_