Allow native_viewport to create new native windows on demand on Android.

shell/android/apk/src/org/chromium/mojo/shell/NfcReceiverActivity.java

 // Copyright 2015 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.mojo.shell;
 
 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
 import android.content.ServiceConnection;
@@ skipping 33 matching lines @@
     @Override
     protected void onNewIntent(Intent intent) {
         super.onNewIntent(intent);
         mPendingIntents.add(intent);
     }
 
     @Override
     public void onShellBound(ShellService shellService) {
         mShellService = shellService;
         finish();
-        Intent intent = new Intent(this, MojoShellActivity.class);
-        intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
-        startActivity(intent);
         while (!mPendingIntents.isEmpty()) {
             Intent pendingIntent = mPendingIntents.remove();
             sendNfcMessages(pendingIntent);
         }
         unbindService(mShellServiceConnection);
     }
 
     @Override
     public void onShellUnbound() {
         mShellService = null;
@@ skipping 12 matching lines @@
         NdefRecord[] records = msg.getRecords();
         for (int i = 0; i < (records.length - 1); i++) {
             byte[] payload = records[i].getPayload();
             if (payload != null) {
                 nfcMessageSink.onNfcMessage(payload);
             }
         }
         nfcMessageSink.close();
     }
 }