VR: Get fallback fonts for set of characters rather than full string.

chrome/browser/android/vr_shell/textures/ui_texture.cc

 // Copyright 2017 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 "chrome/browser/android/vr_shell/textures/ui_texture.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 26 matching lines @@
 }
 
 bool UiTexture::IsRTL() {
   return base::i18n::IsRTL();
 }
 
 gfx::FontList UiTexture::GetFontList(int size, base::string16 text) {
   gfx::Font default_font(kDefaultFontFamily, size);
   std::vector<gfx::Font> fonts{default_font};
 
+  std::set<wchar_t> characters;
+  for (base::i18n::UTF16CharIterator it(&text); !it.end(); it.Advance()) {
+    characters.insert(it.get());
+  }
   // TODO(acondor): Obtain fallback fonts with gfx::GetFallbackFonts
   // (which is not implemented for android yet) in order to avoid
   // querying per character.
 
   sk_sp<SkFontMgr> font_mgr(SkFontMgr::RefDefault());
   std::set<std::string> names;
   // TODO(acondor): Query BrowserProcess to obtain the application locale.
-  for (base::i18n::UTF16CharIterator it(&text); !it.end(); it.Advance()) {
+  for (wchar_t character : characters) {
     sk_sp<SkTypeface> tf(font_mgr->matchFamilyStyleCharacter(
-        default_font.GetFontName().c_str(), SkFontStyle(), nullptr, 0,
-        it.get()));
+        kDefaultFontFamily, SkFontStyle(), nullptr, 0, character));
+
     // TODO(acondor): How should we handle no matching font?
     if (!tf)
       continue;
     SkString sk_name;
     tf->getFamilyName(&sk_name);
     std::string name(sk_name.c_str());
     if (name != kDefaultFontFamily)
       names.insert(name);
   }
   for (const auto& name : names)
     fonts.push_back(gfx::Font(name, size));
   return gfx::FontList(fonts);
 }
 
 }  // namespace vr_shell