Use BCP47 compliant format for locale representation

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

Index: base/android/java/src/org/chromium/base/LocaleUtils.java
diff --git a/base/android/java/src/org/chromium/base/LocaleUtils.java b/base/android/java/src/org/chromium/base/LocaleUtils.java
index 5c26e7a50c28618ad009b7499bd1954b44b4541c..f240e366dd822481ddcf3d19b555e4fbcf3d5e4c 100644
--- a/base/android/java/src/org/chromium/base/LocaleUtils.java
+++ b/base/android/java/src/org/chromium/base/LocaleUtils.java
@@ -4,6 +4,8 @@
 
 package org.chromium.base;
 
+import android.os.Build;
+
 import org.chromium.base.annotations.CalledByNative;
 
 import java.util.Locale;
@@ -19,26 +21,85 @@ public class 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 = locale.getLanguage();
+        String language = languageAdjust(locale.getLanguage());
         String country = locale.getCountry();
 
-        // 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.
+        return country.isEmpty() ? language : language + "-" + country;
+    }
+
+    /**
+     * 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) {

[Seigo Nonaka, 2016/10/17 04:12:15]

"adjust" sounds like bit ambiguous.
How about migrateDeprecatedLanguage?

[ksk1, 2016/10/17 05:06:04]

I think "tl" is not deprecated.

[Yirui Huang, 2016/10/17 10:40:51]

Done.

[Yirui Huang, 2016/10/17 10:40:51]

Done.

+        // 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)) {

[Seigo Nonaka, 2016/10/17 04:12:15]

optional:
you can prepare static map for this purpose, like

private static Map<String, String> DEPRECATED_LANGUAGE_MAP;

static {
  HashMap<String, String> map = new HashMap<>();
  map.put("iw", "he");  // Hebrew
  map.put("ji", "yi");  // Yiddish
  ...
  DEPRECATED_LANGUAGE_MAP = Collections.unmodifiableMap(map);
}

Then,

String newLanguageID = DEPRECATED_LANGUAGE_MAP.get(language);
return newLanguageID == null ? language : newLanguageID;

[Yirui Huang, 2016/10/17 10:40:51]

changed using HashMap, but since this function is called by
ResourceExtractor.java(new commit), I made it public.

[Seigo Nonaka, 2016/10/17 11:30:46]

I don't think we need to expose this function. Please see the comment in
ResourceExtractor

-            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;
+        }
+    }
+
+    /**
+     * This function does the same as Locale.forLanguageTag() when API level is lower than 21.

[Seigo Nonaka, 2016/10/17 04:12:15]

forLanguageTag does more complicated things than simply parsing xx-XX style.
How about,

This function can be used for alternative of Locale.forLanguageTag before API
Level 21.
This function creates Locale object from xx-XX style string where xx is language
code and XX is a country code.

[Yirui Huang, 2016/10/17 10:40:51]

Done.

+     * @return the best representative locale with the language tag that has language and/or
+     * country code.
+     */
+    public static Locale forLanguageTagCompat(String languageTag) {

[Seigo Nonaka, 2016/10/17 04:12:15]

This can be private? if this is public only for testing purpose, please put
@visibleForTesting

[Yirui Huang, 2016/10/17 10:40:52]

Done.

+        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);

[Seigo Nonaka, 2016/10/17 04:12:15]

Look like you don't migrate the deprecated language code. Is the Android after
Lollipop no longer has a problem of deprecated language code? If yes, please
leave a comment.

[Yirui Huang, 2016/10/17 10:40:51]

It seems these three deprecated language codes are withdrawn in ISO 639-2.
(http://www.loc.gov/standards/iso639-2/php/code_changes.php) but it might be
safer to check using updateLanguageForChromium.

[Seigo Nonaka, 2016/10/17 11:30:46]

Okay thanks. Then, looks like Android can still return ISO 639-1 country code.
We should keep this code even for the latest device. 
https://developer.android.com/reference/java/util/Locale.html

+        }
+        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();

[Seigo Nonaka, 2016/10/17 04:12:15]

Same as above. Please check the deprecated language code.

[Yirui Huang, 2016/10/17 10:40:51]

Done.

+        } else {

[Seigo Nonaka, 2016/10/17 04:12:15]

nit: you can drop else here.

[Yirui Huang, 2016/10/17 10:40:51]

Done.

+            return getLocale(locale);
         }
-        return country.isEmpty() ? language : language + "-" + country;
     }
 
     /**