Use BCP47 compliant format for locale representation

base/android/java/src/org/chromium/base/LocaleUtils.java

 // Copyright 2014 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.
 
 package org.chromium.base;
 
+import android.os.Build;
+
 import org.chromium.base.annotations.CalledByNative;
 
 import java.util.Locale;
 
 /**
  * This class provides the locale related methods.
  */
 public class LocaleUtils {
     /**
      * Guards this class from being instantiated.
      */
     private LocaleUtils() {
     }
 
     /**
-     * @return The string for the given locale, translating Android deprecated language codes
-     *         into the modern ones used by Chromium.
+     * @return the string for the given locale with language and/or country code, translating
+     *         Android deprecated language codes into the modern ones used by Chromium.
      */
     public static String getLocale(Locale locale) {
-        String language = getLanguage(locale);
+        String language = languageAdjust(locale.getLanguage());
         String country = locale.getCountry();
 
         return country.isEmpty() ? language : language + "-" + country;
     }
 
     /**
-     * @return The language for the given locale, translating Android deprecated languages codes
-     *         into modern ones used by Chromium.
-     */
-    public static String getLanguage(Locale locale) {
-        String language = locale.getLanguage();
-
-        // Android uses deprecated lanuages codes for Hebrew and Indonesian but Chromium uses the
-        // updated codes. Also, Android uses "tl" while Chromium uses "fil" for Tagalog/Filipino.
-        // So apply a mapping.
+     * Handle the special cases in converting a language code/region code pair into an ISO-639-1
+     * language tag.
+     * @return a updated language code if necessary.
+     **/
+    private static String languageAdjust(String language) {
+        // Android uses deprecated lanuages codes for Hebrew, Yiddish and Indonesian but
+        // Chromium uses the updated codes. Also, Android uses "tl" while Chromium uses "fil"
+        // for Tagalog/Filipino. So apply a mapping.
         // See http://developer.android.com/reference/java/util/Locale.html
         if ("iw".equals(language)) {
-            language = "he";
+            return "he";
+        } else if ("ji".equals(language)) {
+            return "yi";
         } else if ("in".equals(language)) {
-            language = "id";
+            return "id";
         } else if ("tl".equals(language)) {
-            language = "fil";
+            return "fil";
+        } else {
+            return language;
         }
-        return language;
     }
 
     /**
+     * This function does the same as Locale.forLanguageTag() when API level is lower than 21.
+     * @return the best representative locale with the language tag that has language and/or
+     *         country code.
+     */
+    public static Locale forLanguageTagCompat(String languageTag) {
+        if (languageTag.length() == 0) {
+            return new Locale("");
+        }
+        String[] tag = languageTag.split("-");
+        String language = tag[0];
+        if (language.length() != 2 && language.length() != 3) {
+            return new Locale("");
+        }
+        if (tag.length == 1) {
+            language = languageAdjust(languageTag);
+            return new Locale(language);
+        }
+        String country = tag[1];
+        if (country.length() != 2 && country.length() != 3) {
+            return new Locale(language);
+        }
+        return new Locale(language, country);
+    }
+
+    /**
+     * @return the locale that best represents the language tag that has language and/or
+     *         country code.
+     */
+    public static Locale forLanguageTag(String languageTag) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            return Locale.forLanguageTag(languageTag);
+        }
+        return LocaleUtils.forLanguageTagCompat(languageTag);
+    }
+
+    /**
+     * @return a well-formed IETF BCP 47 language tag with language and country code that
+     *         represents this locale.
+     */
+    public static String toLanguageTag(Locale locale) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            return locale.toLanguageTag();
+        }
+        return getLocale(locale);
+    }
+
+    /**
      * @return The default locale, translating Android deprecated language codes into the modern
      *         ones used by Chromium.
      */
     @CalledByNative
     public static String getDefaultLocale() {
         return getLocale(Locale.getDefault());
     }
 
     /**
      * @return The default country code set during install.
      */
     @CalledByNative
     private static String getDefaultCountryCode() {
         CommandLine commandLine = CommandLine.getInstance();
         return commandLine.hasSwitch(BaseSwitches.DEFAULT_COUNTRY_CODE_AT_INSTALL)
                 ? commandLine.getSwitchValue(BaseSwitches.DEFAULT_COUNTRY_CODE_AT_INSTALL)
                 : Locale.getDefault().getCountry();
     }
 
 }