[Autofill] Add support for signin promo on Android

chrome/android/java/src/org/chromium/chrome/browser/signin/SigninPromoUtil.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.signin;
 
 import android.app.Activity;
 import android.text.TextUtils;
 
+import org.chromium.base.annotations.CalledByNative;
 import org.chromium.chrome.browser.multiwindow.MultiWindowUtils;
 import org.chromium.chrome.browser.preferences.ChromePreferenceManager;
 import org.chromium.chrome.browser.preferences.PrefServiceBridge;
 import org.chromium.sync.signin.ChromeSigninController;
+import org.chromium.ui.base.WindowAndroid;
 
 /**
 * Helper functions for promoting sign in.
 */
 public class SigninPromoUtil {
     private SigninPromoUtil() {}
 
     /**
      * Launches the signin promo if it needs to be displayed.
      * @param activity The parent activity.
@@ skipping 10 matching lines @@
 
         String lastSyncName = PrefServiceBridge.getInstance().getSyncLastAccountName();
         if (ChromeSigninController.get(activity).isSignedIn() || !TextUtils.isEmpty(lastSyncName)) {
             return false;
         }
 
         AccountSigninActivity.startAccountSigninActivity(activity, SigninAccessPoint.SIGNIN_PROMO);
         preferenceManager.setSigninPromoShown();
         return true;
     }
+
+    /**
+     * A convenience method to create an AccountSigninActivity, passing the access point as an
+     * intent extra.
+     * @param window WindowAndroid from which to get the Activity/Context.
+     * @param accessPoint for metrics purposes.
+     */
+    @CalledByNative
+    private static void openAccountSigninActivityForPromo(WindowAndroid window, int accessPoint) {
+        Activity activity = window.getActivity().get();
+        if (activity != null) {
+            AccountSigninActivity.startIfAllowed(activity, accessPoint);
+        }
+    }
 }