Use BCP47 compliant format for locale representation

chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java
index a72aad81c285bfe72130ee0c84e5bd3a2403ac1e..7d873c99bcbc6de02fef5d61ec5001fb54607c32 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java
@@ -12,6 +12,7 @@ import org.chromium.base.ApplicationState;
 import org.chromium.base.ApplicationStatus;
 import org.chromium.base.ApplicationStatus.ApplicationStateListener;
 import org.chromium.base.ContextUtils;
+import org.chromium.base.LocaleUtils;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.metrics.RecordHistogram;
@@ -29,7 +30,6 @@ import org.chromium.chrome.browser.util.FeatureUtilities;
 import org.chromium.content.browser.ChildProcessLauncher;
 
 import java.lang.ref.WeakReference;
-import java.util.Locale;
 
 /**
  * Tracks the foreground session state for the Chrome activities.
@@ -182,7 +182,7 @@ public class ChromeActivitySessionTracker {
      */
     private void updateAcceptLanguages() {
         PrefServiceBridge instance = PrefServiceBridge.getInstance();
-        String localeString = Locale.getDefault().toString();  // ex) en_US, de_DE, zh_CN_#Hans
+        String localeString = LocaleUtils.getDefaultLocaleString();
         if (hasLocaleChanged(localeString)) {
             instance.resetAcceptLanguages(localeString);
             // Clear cache so that accept-languages change can be applied immediately.