RenderTextHarfBuzz: Try fallback fonts of the Uniscribe font while shaping

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 3ee533290ca729bb9871427740e29c597c6d1489..33b0349733f3cfc2b312f3d306ed9e750eec01fd 100644
--- a/ui/gfx/render_text_harfbuzz.cc
+++ b/ui/gfx/render_text_harfbuzz.cc
@@ -1104,13 +1104,16 @@ void RenderTextHarfBuzz::ShapeRun(internal::TextRunHarfBuzz* run) {
 
 #if defined(OS_WIN)
   Font uniscribe_font;
+  bool got_uniscribe_font = false;
   const base::char16* run_text = &(GetLayoutText()[run->range.start()]);
   if (GetUniscribeFallbackFont(primary_font, run_text, run->range.length(),
-                               &uniscribe_font) &&
-      CompareFamily(run, uniscribe_font.GetFontName(),
-                    uniscribe_font.GetFontRenderParams(),
-                    &best_family, &best_render_params, &best_missing_glyphs))
-    return;
+                               &uniscribe_font)) {
+    got_uniscribe_font = true;
+    if (CompareFamily(run, uniscribe_font.GetFontName(),
+                      uniscribe_font.GetFontRenderParams(),
+                      &best_family, &best_render_params, &best_missing_glyphs))
+      return;
+  }
 #endif
 
   // Skip the first fallback font, which is |primary_font|.
@@ -1127,6 +1130,24 @@ void RenderTextHarfBuzz::ShapeRun(internal::TextRunHarfBuzz* run) {
       return;
   }
 
+  // Try fonts in the fallback list of the Uniscribe font.

[msw, 2014/10/27 17:28:51]

Shouldn't this be in an #if defined(OS_WIN) block?

[ckocagil, 2014/10/28 03:24:42]

Done.

+  if (got_uniscribe_font) {
+    fallback_families =
+        GetFallbackFontFamilies(uniscribe_font.GetFontName());
+    for (size_t i = 1; i < fallback_families.size(); ++i) {

[Daniel Erat, 2014/10/27 18:49:24]

there's a bunch of duplicated code here. is the GetFallbackFontFamilies() call
expensive, or could you just append this list to the primary font's fallbacks
and have a single loop?

[ckocagil, 2014/10/28 03:24:42]

Done.

+      FontRenderParamsQuery query(false);
+      query.families.push_back(fallback_families[i]);
+      query.pixel_size = run->font_size;
+      query.style = run->font_style;
+      FontRenderParams fallback_render_params =
+          GetFontRenderParams(query, NULL);
+      if (CompareFamily(run, fallback_families[i], fallback_render_params,
+                        &best_family, &best_render_params,
+                        &best_missing_glyphs))
+        return;
+    }
+  }
+
   if (!best_family.empty() &&
       (best_family == run->family ||
        ShapeRunWithFont(run, best_family, best_render_params)))