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

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
diff --git a/ui/gfx/render_text.cc b/ui/gfx/render_text.cc
index 8497aa5bef99a204079b8b47364ee0f284f98910..a3a95f3fe9f3c7a6c14504259521a6145e311d8b 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -1233,6 +1233,11 @@ void RenderText::UpdateLayoutText() {
   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();
 }