Move the USB API tests into app_shell_browsertests.

chrome/test/data/extensions/api_test/usb/device_handling/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;
-
-function getDevices() {
-  usb.getDevices({
-      vendorId: 0,
-      productId: 0
-  }, function(devices) {
-    usb.openDevice(devices[0], function(handle) {
-      usb.closeDevice(handle);
-      chrome.test.succeed();
-    });
-  });
-}
-
-function explicitCloseDevice() {
-  usb.findDevices({
-      vendorId: 0,
-      productId: 0
-  }, function(devices) {
-    usb.closeDevice(devices[0]);
-    chrome.test.succeed();
-  });
-}
-
-chrome.test.runTests([
-    getDevices, explicitCloseDevice
-]);