Revert of Merge HarfBuzz kerning support from Blink

ui/gfx/render_text_harfbuzz.cc

Index: ui/gfx/render_text_harfbuzz.cc
diff --git a/ui/gfx/render_text_harfbuzz.cc b/ui/gfx/render_text_harfbuzz.cc
index 959b06c9a658d5abe409a541748e8c2a0a2f8a33..10e7a1a5276931a44ad6e8ff6643d5a03bba9ed9 100644
--- a/ui/gfx/render_text_harfbuzz.cc
+++ b/ui/gfx/render_text_harfbuzz.cc
@@ -126,50 +126,6 @@
   return true;
 }
 
-hb_position_t GetGlyphKerning(FontData* font_data,
-                              hb_codepoint_t first_glyph,
-                              hb_codepoint_t second_glyph) {
-  SkTypeface* typeface = font_data->paint_.getTypeface();
-  const uint16_t glyphs[2] = { first_glyph, second_glyph };
-  int32_t kerning_adjustments[1] = { 0 };
-
-  if (!typeface->getKerningPairAdjustments(glyphs, 2, kerning_adjustments))
-    return 0;
-
-  SkScalar upm = SkIntToScalar(typeface->getUnitsPerEm());
-  SkScalar size = font_data->paint_.getTextSize();
-  return SkiaScalarToHarfBuzzPosition(
-      SkScalarMulDiv(SkIntToScalar(kerning_adjustments[0]), size, upm));
-}
-
-hb_position_t GetGlyphHorizontalKerning(hb_font_t* font,
-                                        void* data,
-                                        hb_codepoint_t left_glyph,
-                                        hb_codepoint_t right_glyph,
-                                        void* user_data) {
-  FontData* font_data = reinterpret_cast<FontData*>(data);
-  if (font_data->paint_.isVerticalText()) {
-    // We don't support cross-stream kerning.
-    return 0;
-  }
-
-  return GetGlyphKerning(font_data, left_glyph, right_glyph);
-}
-
-hb_position_t GetGlyphVerticalKerning(hb_font_t* font,
-                                      void* data,
-                                      hb_codepoint_t top_glyph,
-                                      hb_codepoint_t bottom_glyph,
-                                      void* user_data) {
-  FontData* font_data = reinterpret_cast<FontData*>(data);
-  if (!font_data->paint_.isVerticalText()) {
-    // We don't support cross-stream kerning.
-    return 0;
-  }
-
-  return GetGlyphKerning(font_data, top_glyph, bottom_glyph);
-}
-
 // Writes the |extents| of |glyph|.
 hb_bool_t GetGlyphExtents(hb_font_t* font,
                           void* data,
@@ -188,6 +144,7 @@
 
   // We don't set callback functions which we can't support.
   // HarfBuzz will use the fallback implementation if they aren't set.
+  // TODO(ckocagil): Merge Blink's kerning funcs.
   if (!font_funcs) {
     // The object created by |hb_font_funcs_create()| below lives indefinitely
     // and is intentionally leaked.
@@ -195,12 +152,8 @@
     hb_font_funcs_set_glyph_func(font_funcs, GetGlyph, 0, 0);
     hb_font_funcs_set_glyph_h_advance_func(
         font_funcs, GetGlyphHorizontalAdvance, 0, 0);
-    hb_font_funcs_set_glyph_h_kerning_func(
-        font_funcs, GetGlyphHorizontalKerning, 0, 0);
     hb_font_funcs_set_glyph_h_origin_func(
         font_funcs, GetGlyphHorizontalOrigin, 0, 0);
-    hb_font_funcs_set_glyph_v_kerning_func(
-        font_funcs, GetGlyphVerticalKerning, 0, 0);
     hb_font_funcs_set_glyph_extents_func(
         font_funcs, GetGlyphExtents, 0, 0);
     hb_font_funcs_make_immutable(font_funcs);