Remove use_ibus variable from gyp file.

ui/ui.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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     'shell_dialogs.gypi',
@@ skipping 588 matching lines @@
           'sources/': [
             ['exclude', '^base/gestures/*'],
           ]
         }],
         ['use_aura==1 and use_ash==0 and OS=="linux"', {
           'sources': [
             'base/linux_ui.cc',
             'base/linux_ui.h',
           ]
         }],
-        ['use_ibus==1', {
-          'dependencies': [
-            '../build/linux/system.gyp:ibus',
-          ],
-        }],
         ['use_glib == 1', {
           'dependencies': [
             # font_gtk.cc uses fontconfig.
             '../build/linux/system.gyp:fontconfig',
             '../build/linux/system.gyp:glib',
             '../build/linux/system.gyp:pangocairo',
             '../build/linux/system.gyp:x11',
             '../build/linux/system.gyp:xext',
             '../build/linux/system.gyp:xfixes',
           ],
@@ skipping 303 matching lines @@
           'link_settings': {
             'libraries': [
               '$(SDKROOT)/System/Library/Frameworks/Cocoa.framework',
             ],
           },
         },
       ],
     }],
   ],
 }