Created fakes for HID-detection screen testing. Initial browsertest added.

device/hid/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.
 
 source_set("hid") {
   sources = [
     "device_monitor_linux.cc",
     "device_monitor_linux.h",
+    "fake_input_service_linux.cc",
+    "fake_input_service_linux.h",
     "hid_collection_info.cc",
     "hid_collection_info.h",
     "hid_connection.cc",
     "hid_connection.h",
     "hid_connection_linux.cc",
     "hid_connection_linux.h",
     "hid_connection_mac.cc",
     "hid_connection_mac.h",
     "hid_connection_win.cc",
     "hid_connection_win.h",
@@ skipping 28 matching lines @@
     "//net",
   ]
 
   if (is_linux) {
     deps += [ "//device/udev_linux" ]
   }
   if (is_chromeos) {
     deps += [ "//chromeos" ]
   }
 }