Make it possible to disable dbus on linux

chrome/chrome_tests_unit.gypi

 # Copyright 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': [
     {
       # This target contains mocks and test utilities that don't belong in
       # production libraries but are used by more than one test executable.
       'target_name': 'test_support_common',
       'type': 'static_library',
@@ skipping 1954 matching lines @@
             ['chromeos==0', {
               'conditions': [
                 ['use_gnome_keyring==1', {
                   # We use a few library functions directly, so link directly.
                   'dependencies': [
                     '../build/linux/system.gyp:gnome_keyring_direct',
                   ],
                 }],
               ],
             }],
+            ['use_dbus==1', {
+              'dependencies': [
+                '../build/linux/system.gyp:dbus',
+                '../dbus/dbus.gyp:dbus_test_support',
+              ],
+            }],
           ],
           'dependencies': [
-            '../build/linux/system.gyp:dbus',
             '../build/linux/system.gyp:gtk',
-            '../dbus/dbus.gyp:dbus_test_support',
           ],
           'sources!': [
             'browser/printing/print_job_unittest.cc',
           ],
         }, { # else: toolkit_uses_gtk != 1
           'sources!': [
             'browser/ui/gtk/tabs/tab_renderer_gtk_unittest.cc',
             '../ui/views/focus/accelerator_handler_gtk_unittest.cc',
           ],
         }],
         ['toolkit_uses_gtk == 1 or chromeos==1 or (OS=="linux" and use_aura==1)', {
           'dependencies': [
             '../build/linux/system.gyp:ssl',
           ],
         }],
         ['use_gnome_keyring == 0', {
           # Disable the GNOME Keyring tests if we are not using it.
           'sources!': [
             'browser/password_manager/native_backend_gnome_x_unittest.cc',
           ],
         }],
-        ['OS=="linux" and use_aura==1', {
+        ['OS=="linux" and use_aura==1 and use_dbus==0', {
           'dependencies': [
             '../build/linux/system.gyp:dbus',
             '../dbus/dbus.gyp:dbus_test_support',
             '../ui/aura/aura.gyp:aura_test_support',
           ],
         }],
         ['OS=="linux" and branding=="Chrome" and target_arch=="ia32"', {
           'configurations': {
             'Release': {
               'ldflags': [
@@ skipping 383 matching lines @@
               # more details.
               'DebugInformationFormat': '3',
               'ProgramDataBaseFileName': '<(PRODUCT_DIR)/unit_tests.exe.pdb',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }