Remove dead code from RenderTextHarffbuzz

Trival dead code.

R=pkasting@chromium.org

Bug: 1025561
Change-Id: I1297bed599a55fd11fedcb810379173b8c17c3c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1979368Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727058}

ui/gfx/render_text_harfbuzz.h

@@ -19,12 +19,6 @@
 
 #include <hb.h>
 
-namespace base {
-namespace i18n {
-class BreakIterator;
-}
-}
-
 namespace gfx {
 
 class Range;
@@ -312,10 +306,6 @@ class GFX_EXPORT RenderTextHarfBuzz : public RenderText {
   bool update_display_run_list_ : 1;
   bool update_display_text_ : 1;
 
-  // ICU grapheme iterator for the layout text. Use GetGraphemeIterator()
-  // to access the iterator.
-  std::unique_ptr<base::i18n::BreakIterator> grapheme_iterator_;
-
   // The total size of the layouted text.
   SizeF total_size_;