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

ui/gfx/render_text_harfbuzz.h

Index: ui/gfx/render_text_harfbuzz.h
diff --git a/ui/gfx/render_text_harfbuzz.h b/ui/gfx/render_text_harfbuzz.h
index f19f04f05290ae892c237c2dcf36fcbd14a85f5d..a4de1f1da70ef60405d51b50a216d59bcd9d0c01 100644
--- a/ui/gfx/render_text_harfbuzz.h
+++ b/ui/gfx/render_text_harfbuzz.h
@@ -5,6 +5,7 @@
 #ifndef UI_GFX_RENDER_TEXT_HARFBUZZ_H_
 #define UI_GFX_RENDER_TEXT_HARFBUZZ_H_
 
+#include "base/i18n/break_iterator.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "third_party/harfbuzz-ng/src/hb.h"
@@ -32,9 +33,16 @@ struct GFX_EXPORT TextRunHarfBuzz {
   // Returns the number of missing glyphs in the shaped text run.
   size_t CountMissingGlyphs() const;
 
-  // Returns the X coordinate of the leading or |trailing| edge of the glyph
-  // starting at |text_index|, relative to the left of the text (not the view).
-  int GetGlyphXBoundary(size_t text_index, bool trailing) const;
+  // Writes the character and glyph ranges of the cluster containing |pos|.
+  void GetClusterAt(size_t pos, Range* chars, Range* glyphs) const;
+
+  // Returns the grapheme bounds at |text_index|. Handles multi-grapheme glyphs.
+  Range GetGraphemeBounds(const base::string16& text,
+                          base::i18n::BreakIterator* grapheme_iterator,
+                          size_t text_index);
+
+  // Returns whether the given shaped run contains any missing glyphs.
+  bool HasMissingGlyphs() const;
 
   int width;
   int preceding_run_widths;
@@ -45,7 +53,7 @@ struct GFX_EXPORT TextRunHarfBuzz {
 
   scoped_ptr<uint16[]> glyphs;
   scoped_ptr<SkPoint[]> positions;
-  scoped_ptr<uint32[]> glyph_to_char;
+  std::vector<uint32> glyph_to_char;
   size_t glyph_count;
 
   skia::RefPtr<SkTypeface> skia_face;
@@ -93,6 +101,8 @@ class GFX_EXPORT RenderTextHarfBuzz : public RenderText {
   friend class RenderTextTest;
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_RunDirection);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_BreakRunsByUnicodeBlocks);
+  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_SubglyphGraphemeCases);
+  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_SubglyphGraphemePartition);
 
   // Return the run index that contains the argument; or the length of the
   // |runs_| vector if argument exceeds the text length or width.