Move DeviceMonitorLinux to //device/core.

device/core/core.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
       'target_name': 'device_core',
       'type': '<(component)',
       'include_dirs': [
         '../..',
       ],
       'defines': [
         'DEVICE_CORE_IMPLEMENTATION',
       ],
       'sources': [
         'device_client.cc',
         'device_client.h',
         'device_info_query_win.cc',
         'device_info_query_win.h',
         'device_monitor_win.cc',
         'device_monitor_win.h',
       ],
       'dependencies': [
         '../../base/base.gyp:base',
+      ],
+      'conditions': [
+        ['use_udev==1', {
+          'dependencies': [
+            '../udev_linux/udev.gyp:udev_linux',
+          ],
+          'sources': [
+            'device_monitor_linux.cc',
+            'device_monitor_linux.h',
+          ],
+        }],
       ]
     },
     {
       'target_name': 'device_core_mocks',
       'type': 'static_library',
       'include_dirs': [
         '../..',
       ],
       'dependencies': [
         '../../testing/gmock.gyp:gmock',
         'device_core',
       ],
       'sources': [
         'mock_device_client.cc',
         'mock_device_client.h',
       ],
     },
   ],
 }