Defer computing localeForHan until needed

third_party/WebKit/Source/platform/fonts/AcceptLanguagesResolver.cpp

 // Copyright 2016 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 "platform/fonts/AcceptLanguagesResolver.h"
 
 #include "platform/LayoutLocale.h"
 
 namespace blink {
 
+static String& currentAcceptLanguages()
+{
+    DEFINE_STATIC_LOCAL(String, s_current, ());
+    return s_current;
+}
+
 void AcceptLanguagesResolver::acceptLanguagesChanged(
     const String& acceptLanguages)
 {
-    LayoutLocale::setLocaleForHan(
-        localeForHanFromAcceptLanguages(acceptLanguages));
+    String& currentValue = currentAcceptLanguages();
+    if (currentValue == acceptLanguages)
+        return;
+
+    currentValue = acceptLanguages;
+    LayoutLocale::invalidateLocaleForHan();
+}
+
+const LayoutLocale* AcceptLanguagesResolver::localeForHan()
+{
+    return localeForHanFromAcceptLanguages(currentAcceptLanguages());
 }
 
 const LayoutLocale* AcceptLanguagesResolver::localeForHanFromAcceptLanguages(
     const String& acceptLanguages)
 {
     // Use the first acceptLanguages that can disambiguate.
     Vector<String> languages;
     acceptLanguages.split(',', languages);
     for (String token : languages) {
         token = token.stripWhiteSpace();
         const LayoutLocale* locale = LayoutLocale::get(AtomicString(token));
         if (locale->hasScriptForHan())
             return locale;
     }
 
     return nullptr;
 }
 
 } // namespace blink