Add plumbing for accessing latest country in variations service in Java

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 ad1bf9998c28898ee62e49faf9e7d574b18f1001..8d955f015334403a99462f92ddbf812ab6ed23ab 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java
@@ -8,6 +8,7 @@ import android.app.Activity;
 import android.app.Application;
 import android.content.SharedPreferences;
 import android.provider.Settings;
+import android.support.annotation.Nullable;
 import android.text.TextUtils;
 
 import org.chromium.base.ApplicationState;
@@ -83,6 +84,14 @@ public class ChromeActivitySessionTracker {
     }
 
     /**
+     * @return The latest country according to the current variations state. Null if not available.
+     */
+    @Nullable
+    public String getVariationsLatestCountry() {
+        return mVariationsSession.getLatestCountry();
+    }
+
+    /**
      * Handle any initialization that occurs once native has been loaded.
      */
     public void initializeWithNative() {