Make it possible to disable udev in linux

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 488 matching lines @@
           'armv7': 0,
         }],
 
         # NSS usage.
         ['(OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris") and use_openssl==0', {
           'use_nss%': 1,
         }, {
           'use_nss%': 0,
         }],
 
+        # libudev usage.  This currently only affects the content layer.
+        ['OS=="linux"', {
+          'use_udev%': 1,
+        }, {
+          'use_udev%': 0,
+        }],
+
         # Flags to use X11 on non-Mac POSIX platforms.
         ['OS=="win" or OS=="mac" or OS=="ios" or OS=="android" or use_ozone==1', {
           'use_x11%': 0,
         }, {
           'use_x11%': 1,
         }],
 
         # Flags to use glib.
         ['OS=="win" or OS=="mac" or OS=="ios" or OS=="android"', {
           'use_glib%': 0,
@@ skipping 322 matching lines @@
     'buildtype%': '<(buildtype)',
     'target_arch%': '<(target_arch)',
     'host_arch%': '<(host_arch)',
     'toolkit_views%': '<(toolkit_views)',
     'ui_compositor_image_transport%': '<(ui_compositor_image_transport)',
     'use_aura%': '<(use_aura)',
     'use_ash%': '<(use_ash)',
     'use_cras%': '<(use_cras)',
     'use_openssl%': '<(use_openssl)',
     'use_nss%': '<(use_nss)',
+    'use_udev%': '<(use_udev)',
     'os_bsd%': '<(os_bsd)',
     'os_posix%': '<(os_posix)',
     'use_dbus%': '<(use_dbus)',
     'use_glib%': '<(use_glib)',
     'use_pango%': '<(use_pango)',
     'use_ozone%': '<(use_ozone)',
     'use_ozone_evdev%': '<(use_ozone_evdev)',
     'toolkit_uses_gtk%': '<(toolkit_uses_gtk)',
     'desktop_linux%': '<(desktop_linux)',
     'use_x11%': '<(use_x11)',
@@ skipping 1266 matching lines @@
       }],
       ['enable_hidpi==1', {
         'defines': ['ENABLE_HIDPI=1'],
       }],
       ['native_discardable_memory==1', {
         'defines': ['DISCARDABLE_MEMORY_ALWAYS_SUPPORTED_NATIVELY'],
       }],
       ['native_memory_pressure_signals==1', {
         'defines': ['SYSTEM_NATIVELY_SIGNALS_MEMORY_PRESSURE'],
       }],
+      ['use_udev==1', {
+        'defines': ['USE_UDEV'],
+      }],
       ['fastbuild!=0', {
         'xcode_settings': {
           'GCC_GENERATE_DEBUGGING_SYMBOLS': 'NO',
         },
         'conditions': [
           ['clang==1', {
             # Clang creates chubby debug information, which makes linking very
             # slow. For now, don't create debug information with clang.  See
             # http://crbug.com/70000
             'conditions': [
@@ skipping 2575 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }