Make sure the dependency on base is exported to components that depend on debus.

dbus/dbus.gyp

 # Copyright (c) 2011 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': 'dbus',
       'type': 'static_library',
       'dependencies': [
         '../base/base.gyp:base',
         '../build/linux/system.gyp:dbus',
       ],
+      'export_dependent_settings': [
+        '../base/base.gyp:base',
+      ],
       'sources': [
         'bus.cc',
         'bus.h',
         'exported_object.cc',
         'exported_object.h',
         'message.cc',
         'message.h',
         'object_proxy.cc',
         'object_proxy.h',
         'scoped_dbus_error.h',
@@ skipping 41 matching lines @@
         'mock_unittest.cc',
         'test_service.cc',
         'test_service.h',
       ],
       'include_dirs': [
         '..',
       ],
     },
   ],
 }