use_udev is more accurate than is_linux for udev gn deps

device/usb/BUILD.gn

 # 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.
 
 assert(!is_android && !is_ios)
 
 source_ids = "//third_party/usb_ids/usb.ids"
 generated_ids = "$target_gen_dir/usb_ids_gen.cc"
 
 source_set("usb") {
@@ skipping 27 matching lines @@
   deps = [
     ":usb_device_ids",
     "//base",
     "//base/third_party/dynamic_annotations",
     "//components/device_event_log",
     "//device/core",
     "//net",
     "//third_party/libusb",
   ]
 
-  if (is_linux) {
+  if (use_udev) {

[tfarina, 2015/08/18 20:09:19]

OK.

https://chromium.googlesource.com/chromium/src/+/master/device/usb/usb.gyp#70

     deps += [ "//device/udev_linux" ]
   }
   if (is_chromeos) {
     deps += [
       "//chromeos",
       "//dbus",
     ]
   }
 }
 
@@ skipping 27 matching lines @@
   args = [
     "-i",
     rebase_path(source_ids, root_build_dir),
     "-o",
     rebase_path(generated_ids, root_build_dir),
   ]
 
   # Only the device_usb target can depend on us.
   visibility = [ ":usb" ]
 }