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

ui/gfx/render_text.cc

 // Copyright (c) 2012 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.
 
 #include "ui/gfx/render_text.h"
 
 #include <algorithm>
 #include <climits>
 
 #include "base/command_line.h"
@@ skipping 1215 matching lines @@
     layout_text_.assign(
         Elide(layout_text_, display_rect_.width(), elide_behavior_));
   }
 
   // Replace the newline character with a newline symbol in single line mode.
   static const base::char16 kNewline[] = { '\n', 0 };
   static const base::char16 kNewlineSymbol[] = { 0x2424, 0 };
   if (!multiline_)
     base::ReplaceChars(layout_text_, kNewline, kNewlineSymbol, &layout_text_);
 
+  grapheme_iterator_.reset(new base::i18n::BreakIterator(layout_text_,
+      base::i18n::BreakIterator::BREAK_CHARACTER));
+  if (!grapheme_iterator_->Init())
+    grapheme_iterator_.reset();
+
   ResetLayout();
 }
 
 base::string16 RenderText::Elide(const base::string16& text,
                                  float available_width,
                                  ElideBehavior behavior) {
   if (available_width <= 0 || text.empty())
     return base::string16();
   if (behavior == ELIDE_EMAIL)
     return ElideEmail(text, available_width);
@@ skipping 177 matching lines @@
   cursor_bounds_ += delta_offset;
 }
 
 void RenderText::DrawSelection(Canvas* canvas) {
   const std::vector<Rect> sel = GetSubstringBounds(selection());
   for (std::vector<Rect>::const_iterator i = sel.begin(); i < sel.end(); ++i)
     canvas->FillRect(*i, selection_background_focused_color_);
 }
 
 }  // namespace gfx