Disable CJK specific generic font families for monospace on Android

third_party/WebKit/Source/platform/fonts/android/FontCacheAndroid.cpp

 /*
  * Copyright (c) 2011 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 33 matching lines @@
     RefPtr<SkFontMgr> fm = adoptRef(SkFontMgr::RefDefault());
     AtomicString familyName = getFamilyNameForCharacter(fm.get(), c, fontDescription, fallbackPriority);
     if (familyName.isEmpty())
         return getLastResortFallbackFont(fontDescription, DoNotRetain);
     return fontDataFromFontPlatformData(getFontPlatformData(fontDescription, FontFaceCreationParams(familyName)), DoNotRetain);
 }
 
 // static
 AtomicString FontCache::getGenericFamilyNameForScript(const AtomicString& familyName, const FontDescription& fontDescription)
 {
+    // If monospace, do not apply CJK hack to find i18n fonts, because
+    // i18n fonts are likely not monospace. Monospace is mostly used
+    // for code, but when i18n characters appear in monospace, system
+    // fallback can still render the characters.

[drott, 2016/08/30 08:18:58]

Looks okay to me but let's file a bug to keep track of this and find a better
way to encode such choices in fonts.xml. Would be great if you could follow up
with the Android fonts people on what should be the best way to address this
problem.

+    if (familyName == FontFamilyNames::webkit_monospace)
+        return familyName;
+
     // This is a hack to use the preferred font for CJK scripts.
     // FIXME: Use new Skia API once Android system supports per-family and per-script fallback fonts.
     UChar32 examplerChar;
     switch (fontDescription.script()) {
     case USCRIPT_SIMPLIFIED_HAN:
     case USCRIPT_TRADITIONAL_HAN:
     case USCRIPT_KATAKANA_OR_HIRAGANA:
         examplerChar = 0x4E00; // A common character in Japanese and Chinese.
         break;
     case USCRIPT_HANGUL:
         examplerChar = 0xAC00;
         break;
     default:
         // For other scripts, use the default generic family mapping logic.
         return familyName;
     }
 
     RefPtr<SkFontMgr> fm = adoptRef(SkFontMgr::RefDefault());
     return getFamilyNameForCharacter(fm.get(), examplerChar, fontDescription, FontFallbackPriority::Text);
 }
 
 } // namespace blink