Remove the usbPrivate API.

extensions/common/api/usb_private.idl

-// Copyright 2014 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.
-
-// Use the <code>chrome.usbPrivate</code> API to interact with connected USB
-// devices. This API provides private extensions to the <code>chrome.usb</code>
-// API which should only be available to trusted pages.
-namespace usbPrivate {
-
-  dictionary DeviceInfo {
-    long vendorId;  // idVendor from the device
-    long productId;  // idProduct from the device
-
-    // Vendor and product names from an internal database.
-    DOMString? vendorName;
-    DOMString? productName;
-
-    // iManufacturer, iProduct and iSerial strings from the device.
-    DOMString? manufacturerString;
-    DOMString? productString;
-    DOMString? serialString;
-  };
-
-  callback GetDevicesCallback = void (long[] deviceIds);
-  callback GetDeviceInfoCallback = void (DeviceInfo deviceInfo);
-
-  interface Functions {
-    // Lists USB devices matching any of the given filters.
-    // |filters|: The properties to search for on target devices.
-    // |callback|: Invoked with a list of device IDs on complete.
-    static void getDevices(usb.DeviceFilter[] filters,
-                           GetDevicesCallback callback);
-
-    // Gets basic display information about a device.
-    // |deviceId|: The device ID (from |getDevices|).
-    // |callback|: Invoked with |DeviceInfo| from the device.
-    static void getDeviceInfo(long deviceId, GetDeviceInfoCallback callback);
-  };
-};