Enable variations restrict param for Java-side fetches.

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 e92b1e9fc81fe71efc0ff8f2b5a160e4658bffd2..ad1bf9998c28898ee62e49faf9e7d574b18f1001 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivitySessionTracker.java
@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser;
 
 import android.app.Activity;
+import android.app.Application;
 import android.content.SharedPreferences;
 import android.provider.Settings;
 import android.text.TextUtils;
@@ -12,6 +13,7 @@ import android.text.TextUtils;
 import org.chromium.base.ApplicationState;
 import org.chromium.base.ApplicationStatus;
 import org.chromium.base.ApplicationStatus.ApplicationStateListener;
+import org.chromium.base.Callback;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.LocaleUtils;
 import org.chromium.base.ThreadUtils;
@@ -47,7 +49,7 @@ public class ChromeActivitySessionTracker {
     // Used to trigger variation changes (such as seed fetches) upon application foregrounding.
     private VariationsSession mVariationsSession;
 
-    private ChromeApplication mApplication;
+    private Application mApplication;
     private boolean mIsInitialized;
     private boolean mIsStarted;
     private boolean mIsFinishedCachingNativeFlags;
@@ -67,7 +69,17 @@ public class ChromeActivitySessionTracker {
      * @see #getInstance()
      */
     protected ChromeActivitySessionTracker() {
-        mApplication = (ChromeApplication) ContextUtils.getApplicationContext();
+        mApplication = (Application) ContextUtils.getApplicationContext();
+        mVariationsSession = AppHooks.get().createVariationsSession();
+    }
+
+    /**
+     * Asynchronously returns the value of the "restrict" URL param that the variations service
+     * should use for variation seed requests.
+     * @param callback Callback that will be called with the param value when available.
+     */
+    public void getVariationsRestrictModeValue(Callback<String> callback) {
+        mVariationsSession.getRestrictModeValue(mApplication, callback);
     }
 
     /**
@@ -81,7 +93,6 @@ public class ChromeActivitySessionTracker {
         assert !mIsStarted;
 
         ApplicationStatus.registerApplicationStateListener(createApplicationStateListener());
-        mVariationsSession = AppHooks.get().createVariationsSession();
     }
 
     /**