RenderTextHarfBuzz: Try fallback fonts of the Uniscribe font while shaping

ui/gfx/render_text_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/render_text_win.h"
 
 #include <algorithm>
 
 #include "base/i18n/break_iterator.h"
 #include "base/i18n/char_iterator.h"
@@ skipping 1015 matching lines @@
       return;
     if (missing_count < best_partial_font_missing_char_count) {
       best_partial_font_missing_char_count = missing_count;
       best_partial_font = current_font;
     }
   }
 
   // Try finding a fallback font using a meta file.
   // TODO(msw|asvitkine): Support RenderText's font_list()?
   Font uniscribe_font;
+  bool got_uniscribe_font = false;
   if (GetUniscribeFallbackFont(original_font, run_text, run_length,
                                &uniscribe_font)) {
+    got_uniscribe_font = true;
     current_font = uniscribe_font;
     missing_count = CountCharsWithMissingGlyphs(run,
         ShapeTextRunWithFont(run, current_font));
     if (missing_count == 0) {
       successful_substitute_fonts_[original_font.GetFontName()] = current_font;
       return;
     }
     if (missing_count < best_partial_font_missing_char_count) {
       best_partial_font_missing_char_count = missing_count;
       best_partial_font = current_font;
@@ skipping 11 matching lines @@
       successful_substitute_fonts_[original_font.GetFontName()] = current_font;
       return;
     }
     if (missing_count < best_partial_font_missing_char_count) {
       best_partial_font_missing_char_count = missing_count;
       best_partial_font = current_font;
     }
   }
 
   // Try fonts in the fallback list of the Uniscribe font.
-  fonts = GetFallbackFontFamilies(uniscribe_font.GetFontName());
-  for (size_t i = 1; i < fonts.size(); ++i) {
-    current_font = Font(fonts[i], original_font.GetFontSize());
-    missing_count = CountCharsWithMissingGlyphs(run,
-      ShapeTextRunWithFont(run, current_font));
-    if (missing_count == 0) {
-      successful_substitute_fonts_[original_font.GetFontName()] = current_font;
-      return;
-    }
-    if (missing_count < best_partial_font_missing_char_count) {
-      best_partial_font_missing_char_count = missing_count;
-      best_partial_font = current_font;
+  if (got_uniscribe_font) {
+    fonts = GetFallbackFontFamilies(uniscribe_font.GetFontName());
+    for (size_t i = 1; i < fonts.size(); ++i) {
+      current_font = Font(fonts[i], original_font.GetFontSize());
+      missing_count = CountCharsWithMissingGlyphs(run,
+          ShapeTextRunWithFont(run, current_font));
+      if (missing_count == 0) {
+        successful_substitute_fonts_[original_font.GetFontName()] =
+            current_font;
+        return;
+      }
+      if (missing_count < best_partial_font_missing_char_count) {
+        best_partial_font_missing_char_count = missing_count;
+        best_partial_font = current_font;
+      }
     }
   }
 
   // If a font was able to partially display the run, use that now.
   if (best_partial_font_missing_char_count < static_cast<int>(run_length)) {
     // Re-shape the run only if |best_partial_font| differs from the last font.
     if (best_partial_font.GetNativeFont() != run->font.GetNativeFont())
       ShapeTextRunWithFont(run, best_partial_font);
     return;
   }
@@ skipping 152 matching lines @@
   size_t position = LayoutIndexToTextIndex(run->range.end());
   position = IndexOfAdjacentGrapheme(position, CURSOR_BACKWARD);
   return SelectionModel(position, CURSOR_FORWARD);
 }
 
 RenderText* RenderText::CreateNativeInstance() {
   return new RenderTextWin;
 }
 
 }  // namespace gfx