Take Accept-Language into account in CJK font fallback for Windows

third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp

 /*
  * Copyright (C) 2006, 2007 Apple Computer, Inc.
  * Copyright (c) 2006, 2007, 2008, 2009, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 34 matching lines @@
 HashMap<String, RefPtr<SkTypeface>>* FontCache::s_sideloadedFonts = 0;
 
 // Cached system font metrics.
 AtomicString* FontCache::s_menuFontFamilyName = 0;
 int32_t FontCache::s_menuFontHeight = 0;
 AtomicString* FontCache::s_smallCaptionFontFamilyName = 0;
 int32_t FontCache::s_smallCaptionFontHeight = 0;
 AtomicString* FontCache::s_statusFontFamilyName = 0;
 int32_t FontCache::s_statusFontHeight = 0;
 
+UScriptCode FontCache::m_preferredScriptForHan = USCRIPT_COMMON;
+
 namespace {
 
 int32_t ensureMinimumFontHeightIfNeeded(int32_t fontHeight)
 {
     // Adjustment for codepage 936 to make the fonts more legible in Simplified Chinese.
     // Please refer to LayoutThemeFontProviderWin.cpp for more information.
     return (fontHeight < 12.0f) && (GetACP() == 936) ? 12.0f : fontHeight;
 }
 
 } // namespace
@@ skipping 40 matching lines @@
     } else {
         fontManager = SkFontMgr_New_GDI();
         // Subpixel text positioning is not supported by the GDI backend.
         s_useSubpixelPositioning = false;
     }
 
     ASSERT(fontManager);
     m_fontManager = adoptPtr(fontManager);
 }
 
-void FontCache::acceptLanguagesChanged(const String&)
+void FontCache::acceptLanguagesChanged(const String& acceptLanguages)
 {
-    // TODO(kojii): Take acceptLanguages into account for ambiguos scripts.
+    // Use the UI locale if it can disambiguate the Unified Han.
+    // Since Chrome synchronizes the ICU default locale with its UI locale,
+    // this ICU locale tells the current UI locale of Chrome.
+    m_preferredScriptForHan = scriptCodeForHanFromLocale(
+        icu::Locale::getDefault().getName(), '_');
+    if (m_preferredScriptForHan != USCRIPT_COMMON)
+        return;
+
+    // Use acceptLanguages if it has languages that can disambiguate.
+    Vector<String> languages;
+    acceptLanguages.split(',', languages);
+    for (String token : languages) {
+        token = token.stripWhiteSpace();
+        m_preferredScriptForHan = scriptCodeForHanFromLocale(token);
+        if (m_preferredScriptForHan != USCRIPT_COMMON)
+            return;
+    }
 }
 
 // Given the desired base font, this will create a SimpleFontData for a specific
 // font that can be used to render the given range of characters.
 PassRefPtr<SimpleFontData> FontCache::fallbackFontForCharacter(
     const FontDescription& fontDescription, UChar32 character,
     const SimpleFontData* originalFontData)
 {
     // First try the specified font with standard style & weight.
     if (fontDescription.style() == FontStyleItalic
@@ skipping 296 matching lines @@
         if (typefacesMatchesFamily(tf.get(), family)) {
             result->setMinSizeForSubpixel(minSizeForSubpixelForFont);
             break;
         }
     }
 
     return result.release();
 }
 
 } // namespace blink