Hide X11 dependencies when use_x11=0.

tools/android/forwarder2/forwarder.gyp

 # 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.
 
 {
   'targets': [
     {
       'target_name': 'forwarder2',
       'type': 'none',
       'dependencies': [
@@ skipping 44 matching lines @@
         'pipe_notifier.cc',
         'socket.cc',
       ],
     },
     {
       'target_name': 'host_forwarder',
       'type': 'executable',
       'toolsets': ['host'],
       'dependencies': [
         '../../../base/base.gyp:base',
-        '../../../build/linux/system.gyp:x11',
         '../common/common.gyp:android_tools_common',
       ],
       'include_dirs': [
         '../../..',
       ],
       'sources': [
         'command.cc',
         'common.cc',
         'daemon.cc',
         'forwarder.cc',
         'forwarders_manager.cc',
         'host_controller.cc',
         'host_forwarder_main.cc',
         'pipe_notifier.cc',
         'socket.cc',
-        # TODO(pliard): Remove this and x11 dependency above. This is needed
-        # to avoid undefined references at link time.
+        # TODO(pliard): Remove this. This is needed to avoid undefined
+        # references at link time.
         '../../../base/message_loop/message_pump_glib.cc',
         '../../../base/message_loop/message_pump_gtk.cc',
       ],
     },
   ],
 }