Move UsbService to its own component.

components/components.gyp

 # 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.
 
 {
   'variables': {
     # This turns on e.g. the filename-based detection of which
     # platforms to include source files on (e.g. files ending in
     # _mac.h or _mac.cc are only compiled on MacOSX).
     'chromium_code': 1,
@@ skipping 37 matching lines @@
         'navigation_interception.gypi',
         'plugins.gypi',
         'sessions.gypi',
         'storage_monitor.gypi',
         'visitedlink.gypi',
         'web_contents_delegate_android.gypi',
         'web_modal.gypi',
         'wifi.gypi',
       ],
     }],
+    ['OS != "ios" and OS != "android"', {
+      'includes': [
+        'usb_service.gypi',
+      ]
+    }],
     ['android_webview_build == 0', {
       # Android WebView fails to build if a dependency on sync.gyp:sync is
       # introduced.
       'includes': [
         'sync_driver.gypi',
       ],
     }],
   ],
 }