Cleanup: Merge device/udev_linux/udev.{cc,h} into device/udev_linux/scoped_udev.h.

device/udev_linux/BUILD.gn

 # 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.
 
 import("//build/config/features.gni")
 
 if (use_udev) {
   source_set("udev_linux") {
     sources = [
-      "udev.cc",
-      "udev.h",
+      "scoped_udev.h",
     ]
 
     deps = [
       "//base",
     ]
 
     configs += [
       "//build/config/linux:udev",
     ]
   }
 }