Bug 1847701 - Accept-language format should be language-region format like Dekstop and Chrome/Android. r=geckoview-reviewers,necko-reviewers,platform-i18n-reviewers,valentin

As spec (RFC 7231), accept-language can accept language tag (BCP 47).

Currently, Firefox Android uses `Locale.toLanguageTag` API. But it may
append variant and extensions etc.

But Chrome/Android and desktop browser use <language>-<region> format for
this header, so we should use same format for compatibility.

Differential Revision: https://phabricator.services.mozilla.com/D203121

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/LocaleTest.kt

@@ -40,4 +40,16 @@ class LocaleTest : BaseSessionTest() {
             equalTo(listOf("en-GB", "en-US", "en-FR")),
         )
     }
+
+    @Test
+    fun acceptLangaugeFormat() {
+        // No way to override default language settings from unit test.
+        // So we only test this on current settings.
+
+        val intlAcceptLanauge = "intl.accept_languages"
+        val prefValue = (sessionRule.getPrefs(intlAcceptLanauge)[0] as String).split(",")
+        for (value in prefValue) {
+            assertThat("Accept-Lanauge format should be language or language-region", value.filter { it == '-' }.count(), lessThanOrEqualTo(1))
+        }
+    }
 }

mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoAppShell.java

@@ -46,7 +46,6 @@ import android.os.Looper;
 import android.os.PowerManager;
 import android.os.Vibrator;
 import android.provider.Settings;
-import android.text.TextUtils;
 import android.util.Log;
 import android.view.ContextThemeWrapper;
 import android.view.Display;
@@ -1527,20 +1526,6 @@ public class GeckoAppShell {
     }
   }
 
-  private static String getLanguageTag(final Locale locale) {
-    final StringBuilder out = new StringBuilder(locale.getLanguage());
-    final String country = locale.getCountry();
-    final String variant = locale.getVariant();
-    if (!TextUtils.isEmpty(country)) {
-      out.append('-').append(country);
-    }
-    if (!TextUtils.isEmpty(variant)) {
-      out.append('-').append(variant);
-    }
-    // e.g. "en", "en-US", or "en-US-POSIX".
-    return out.toString();
-  }
-
   @WrapForJNI
   public static String[] getDefaultLocales() {
     // XXX We may have to convert some language codes such as "id" vs "in".

mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoRuntimeSettings.java

@@ -1056,7 +1056,7 @@ public final class GeckoRuntimeSettings extends RuntimeSettings {
       }
     }
     // OS prefs come second:
-    for (final String locale : getDefaultLocales()) {
+    for (final String locale : getSystemLocalesForAcceptLanguage()) {
       final String localeLowerCase = locale.toLowerCase(Locale.ROOT);
       if (!locales.containsKey(localeLowerCase)) {
         locales.put(localeLowerCase, locale);
@@ -1066,32 +1066,29 @@ public final class GeckoRuntimeSettings extends RuntimeSettings {
     return TextUtils.join(",", locales.values());
   }
 
-  private static String[] getDefaultLocales() {
+  private static String[] getSystemLocalesForAcceptLanguage() {
     if (VERSION.SDK_INT >= 24) {
       final LocaleList localeList = LocaleList.getDefault();
       final String[] locales = new String[localeList.size()];
       for (int i = 0; i < localeList.size(); i++) {
-        locales[i] = localeList.get(i).toLanguageTag();
+        // accept-language should be language or language-region format.
+        locales[i] = getLanguageTagForAcceptLanguage(localeList.get(i));
       }
       return locales;
     }
     final String[] locales = new String[1];
     final Locale locale = Locale.getDefault();
-    locales[0] = locale.toLanguageTag();
+    locales[0] = getLanguageTagForAcceptLanguage(locale);
     return locales;
   }
 
-  private static String getLanguageTag(final Locale locale) {
+  private static String getLanguageTagForAcceptLanguage(final Locale locale) {
     final StringBuilder out = new StringBuilder(locale.getLanguage());
     final String country = locale.getCountry();
-    final String variant = locale.getVariant();
     if (!TextUtils.isEmpty(country)) {
       out.append('-').append(country);
     }
-    if (!TextUtils.isEmpty(variant)) {
-      out.append('-').append(variant);
-    }
-    // e.g. "en", "en-US", or "en-US-POSIX".
+    // e.g. "en", "en-US"
     return out.toString();
   }