Remove obsolete chromeos specific code

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': [
     'ui_resources.gypi',
@@ skipping 148 matching lines @@
         'base/gtk/gtk_signal.h',
         'base/gtk/gtk_signal_registrar.cc',
         'base/gtk/gtk_signal_registrar.h',
         'base/gtk/gtk_windowing.cc',
         'base/gtk/gtk_windowing.h',
         'base/gtk/owned_widget_gtk.cc',
         'base/gtk/owned_widget_gtk.h',
         'base/gtk/scoped_gobject.h',
         'base/gtk/scoped_region.cc',
         'base/gtk/scoped_region.h',
-        'base/gtk/tooltip_window_gtk.cc',
-        'base/gtk/tooltip_window_gtk.h',
         'base/hit_test.h',
         'base/javascript_message_type.h',
         'base/keycodes/keyboard_code_conversion.cc',
         'base/keycodes/keyboard_code_conversion.h',
         'base/keycodes/keyboard_code_conversion_gtk.cc',
         'base/keycodes/keyboard_code_conversion_gtk.h',
         'base/keycodes/keyboard_code_conversion_mac.h',
         'base/keycodes/keyboard_code_conversion_mac.mm',
         'base/keycodes/keyboard_code_conversion_win.cc',
         'base/keycodes/keyboard_code_conversion_win.h',
@@ skipping 546 matching lines @@
                 'shutil.copyfile(\'<(ui_copy_target)\', \'<(ui_copy_dest)\'); ' \
                 'os.chmod(\'<(ui_copy_dest)\', 0700)'
               ]
             }
           ],
         },
       ],
     }],
   ],
 }