Move the USB API tests into app_shell_browsertests.

extensions/test/data/api_test/usb/zero_length_transfer/test.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.
 
 var usb = chrome.usb;
 
 var tests = [
   function zeroLengthTransfer() {
     usb.findDevices({vendorId: 0, productId: 0}, function(devices) {
       var device = devices[0];
       var transfer = new Object();
       transfer.direction = "out";
       transfer.endpoint = 1;
       transfer.data = new ArrayBuffer(0);
       usb.bulkTransfer(device, transfer, function (result) {
         chrome.test.succeed();
       });
     });
   },
 ];
 
 chrome.test.runTests(tests);