Move the USB API tests into app_shell_browsertests.

extensions/test/data/api_test/usb/list_interfaces/test.js

 // Copyright (c) 2013 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.
 
 var usb = chrome.usb;
 
 var tests = [
   function listInterfaces() {
     usb.findDevices({vendorId: 0, productId: 0}, function (devices) {
       var device = devices[0];
       usb.listInterfaces(device, function (result) {
         chrome.test.succeed();
       });
     });
   }
 ];
 
 chrome.test.runTests(tests);