Support multiple locales string for accept language list

chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PwsClientImpl.java

Index: chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PwsClientImpl.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PwsClientImpl.java b/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PwsClientImpl.java
index 2bd35ad4d8e3bba2dd24ddf461955c3a54641e7d..784b2c869c63db551b1cdc9a33cb0fe1aa644fa4 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PwsClientImpl.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PwsClientImpl.java
@@ -8,6 +8,7 @@ import android.content.Context;
 import android.graphics.Bitmap;
 import android.os.AsyncTask;
 import android.os.Build;
+import android.text.TextUtils;
 
 import org.chromium.base.Log;
 import org.chromium.base.ThreadUtils;
@@ -25,7 +26,9 @@ import org.json.JSONObject;
 import java.net.MalformedURLException;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Formatter;
+import java.util.HashSet;
 import java.util.Locale;
 
 /**
@@ -263,35 +266,55 @@ class PwsClientImpl implements PwsClient {
      * Get the language code for the default locale and prepend it to the Accept-Language string if
      * it isn't already present. The logic should match PrependToAcceptLanguagesIfNecessary in
      * chrome/browser/android/preferences/pref_service_bridge.cc
-     * @param locale A string representing the default locale.
+     * @param locales A string representing a default locale or a list of default locales.
      * @param acceptLanguages The default language list for the language of the user's locale.
      * @return An updated language list.
      */
     @VisibleForTesting
-    static String prependToAcceptLanguagesIfNecessary(String locale, String acceptLanguages)
-    {
-        if (locale.length() != 5 || locale.charAt(2) != '_') {
-            return acceptLanguages;
-        }
+    static String prependToAcceptLanguagesIfNecessary(String locales, String acceptLanguages) {
+        String locale_string = locales + "," + acceptLanguages;

[Maria, 2016/10/07 19:14:29]

style: use camelCase for variable names in Java here and below

[Yirui Huang, 2016/10/09 05:11:37]

Done.

+        String[] locale_list = locale_string.split(",");
+
+        HashSet<String> seen_locales = new HashSet<String>();

[Maria, 2016/10/07 19:14:29]

nit: can use HashSet<>() and ArrayList<>() etc here and below

[Yirui Huang, 2016/10/09 05:11:37]

Done.

+        ArrayList<String> unique_list = new ArrayList<String>();
+        for (String locale : locale_list) {
+            // TODO(yirui): Support BCP47 compliant format including 3-letter country code,
+            // '-' separator and missing country case.
+            if (locale.length() != 5 || (locale.charAt(2) != '_' && locale.charAt(2) != '-')) {
+                // Skip checking not well formed locales.
+                continue;
+            }
 
-        String language = locale.substring(0, 2);
-        String region = locale.substring(3);
-        String languageTag = makeLanguageTag(language, region);
+            String language = locale.substring(0, 2);
+            String country = locale.substring(3);
+            String languageTag = makeLanguageTag(language, country);
 
-        if (acceptLanguages.contains(languageTag)) {
-            return acceptLanguages;
+            if (seen_locales.contains(languageTag)) {
+                continue;
+            }
+            unique_list.add(languageTag);
+            seen_locales.add(languageTag);
         }
 
-        Formatter parts = new Formatter();
-        parts.format("%s,", languageTag);
         // If language is not in the accept languages list, also add language code.
-        // This will work with the IDS_ACCEPT_LANGUAGES localized strings bundled with Chrome but
-        // may fail on arbitrary lists of language tags due to differences in case and whitespace.
-        if (!acceptLanguages.contains(language + ",") && !acceptLanguages.endsWith(language)) {
-            parts.format("%s,", language);
+        // A language code should only be inserted after the last languageTag that
+        // contains that language.
+        // This will work with the IDS_ACCEPT_LANGUAGE localized strings bundled
+        // with Chrome but may fail on arbitrary lists of language tags due to
+        // differences in case and whitespace.
+        HashSet<String> seen_languages = new HashSet<String>();
+        ArrayList<String> output_list = new ArrayList<String>();
+        for (int i = unique_list.size() - 1; i >= 0; i--) {
+            String locale_add = unique_list.get(i);
+            String language_add = locale_add.substring(0, 2);
+            if (!seen_languages.contains(language_add)) {
+                seen_languages.add(language_add);
+                output_list.add(language_add);
+            }
+            output_list.add(locale_add);
         }
-        parts.format("%s", acceptLanguages);
-        return parts.toString();
+        Collections.reverse(output_list);
+        return TextUtils.join(",", output_list);
     }
 
     /**