WebUI: Move test_browser_proxy.js one level up.

chrome/test/data/webui/settings/system_page_tests.js

 // 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.
 
 /** @const {boolean} */
 var HARDWARE_ACCELERATION_AT_STARTUP = true;
 
 /**
  * @constructor
  * @extends {TestBrowserProxy}

[rbpotter, 2017/06/07 00:32:01]

Same here.

[dpapad, 2017/06/07 00:42:54]

Done.

  * @implements {settings.SystemPageBrowserProxy}
  */
 function TestSystemPageBrowserProxy() {
-  settings.TestBrowserProxy.call(this, ['showProxySettings']);
+  test.TestBrowserProxy.call(this, ['showProxySettings']);
 }
 
 TestSystemPageBrowserProxy.prototype = {
-  __proto__: settings.TestBrowserProxy.prototype,
+  __proto__: test.TestBrowserProxy.prototype,
 
   /** @override */
   showProxySettings: function() {
     this.methodCalled('showProxySettings');
   },
 
   /** @override */
   wasHardwareAccelerationEnabledAtStartup: function() {
     return HARDWARE_ACCELERATION_AT_STARTUP;
   },
@@ skipping 102 matching lines @@
     });
     Polymer.dom.flush();
 
     // When managed by policy directly, we disable the ability to show proxy
     // settings.
     expectFalse(control.hasAttribute('actionable'));
     expectNotEquals(null, control.querySelector('cr-policy-pref-indicator'));
     expectTrue(showProxyButton.hidden);
   });
 });