Fix ambiguity in API if no matching system language is found

include/ports/SkTypeface_android.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkTypeface_android_DEFINED
 #define SkTypeface_android_DEFINED
@@ skipping 18 matching lines @@
 SK_API bool SkGetFallbackFamilyNameForChar(SkUnichar uni, SkString* name);
 
 /**
  *  Get the family name of the font in the fallback font list containing
  *  the specified character taking into account the provided language. This
  *  function also assumes the only families with the elegant or default variants
  *  will be returned.
  *
  *  @param uni  The unicode character to use for the lookup.
  *  @param lang The null terminated string representing the BCP 47 language
- *              identifier for the preferred language
+ *              identifier for the preferred language. If there is no unique
+ *              fallback chain for that language the system's default language
+ *              will be used.
  *  @param name The family name of the font file containing the unicode character
  *              in the preferred language
  *  @return     true if a font is found and false otherwise
  */
 SK_API bool SkGetFallbackFamilyNameForChar(SkUnichar uni, const char* lang, SkString* name);
 
 /**
  *  For test only.
  *  Load font config from given xml files, instead of those from Android system.
  */
@@ skipping 51 matching lines @@
  *                   unref() when they are done.
  */
 SK_API SkTypeface* SkCreateTypefaceForScriptNG(hb_script_t script, SkTypeface::Style style,
         SkPaintOptionsAndroid::FontVariant fontVariant = SkPaintOptionsAndroid::kDefault_Variant);
 
 SK_API SkTypeface* SkCreateTypefaceForScript(HB_Script script, SkTypeface::Style style,
         SkPaintOptionsAndroid::FontVariant fontVariant = SkPaintOptionsAndroid::kDefault_Variant);
 
 #endif // #ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
 #endif // #ifndef SkTypeface_android_DEFINED