Remove chrome://welcome page.

chrome/browser/resources/about_welcome_android/about_welcome_android.js

-// Copyright (c) 2012 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.
-
-// File Description:
-//     Contains all the necessary functions for rendering the Welcome page on
-//     Android.
-
-cr.define('welcome', function() {
-  'use strict';
-
-  function initialize() {
-    // Disable context menus.
-    document.body.oncontextmenu = function(e) {
-      e.preventDefault();
-    }
-
-    $('settings').onclick = function() {
-      chrome.send('showSyncSettings');
-    };
-
-    var tosLink = $('tos-link');
-    if (tosLink) {
-      tosLink.onclick = function() {
-        chrome.send('showTermsOfService');
-      };
-    }
-
-    // Set visibility of terms of service footer.
-    $('tos-footer').hidden = !loadTimeData.getBoolean('tosVisible');
-
-    // Set the initial visibility for the sync footer.
-    chrome.send('updateSyncFooterVisibility');
-  }
-
-  /**
-   * Sets the visibility of the sync footer.
-   * @param {boolean} isVisible Whether the sync footer should be visible.
-   */
-  function setSyncFooterVisible(isVisible) {
-    $('sync-footer').hidden = !isVisible;
-  }
-
-  // Return an object with all of the exports.
-  return {
-    initialize: initialize,
-    setSyncFooterVisible: setSyncFooterVisible,
-  };
-});
-
-document.addEventListener('DOMContentLoaded', welcome.initialize);