Remove balloon notification code. The last user was the Linux GTK port but that's deleted now.

chrome/chrome_nibs.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.
 
 # This gyp file creates a fake target that is used to generate a minimal Xcode
 # project, useful for editing XIB files.
 #
 # The sole target is called "chrome_nibs" and its sources are the minimum
 # dependency set for all of the classes referred to by XIB files. If you are
 # editing or adding a new XIB file, ensure that any classes to which you refer
@@ skipping 164 matching lines @@
         'browser/ui/cocoa/location_bar/autocomplete_text_field_cell.h',
         'browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm',
         'browser/ui/cocoa/login_prompt_cocoa.h',
         'browser/ui/cocoa/login_prompt_cocoa.mm',
         'browser/ui/cocoa/menu_button.h',
         'browser/ui/cocoa/menu_button.mm',
         'browser/ui/cocoa/multi_key_equivalent_button.h',
         'browser/ui/cocoa/multi_key_equivalent_button.mm',
         'browser/ui/cocoa/new_tab_button.h',
         'browser/ui/cocoa/new_tab_button.mm',
-        'browser/ui/cocoa/notifications/balloon_controller.h',
-        'browser/ui/cocoa/notifications/balloon_controller.mm',
-        'browser/ui/cocoa/notifications/balloon_view.h',
-        'browser/ui/cocoa/notifications/balloon_view.mm',
         'browser/ui/cocoa/nsmenuitem_additions.h',
         'browser/ui/cocoa/nsmenuitem_additions.mm',
         'browser/ui/cocoa/nsview_additions.h',
         'browser/ui/cocoa/nsview_additions.mm',
         'browser/ui/cocoa/one_click_signin_view_controller.h',
         'browser/ui/cocoa/one_click_signin_view_controller.mm',
         'browser/ui/cocoa/screen_capture_notification_ui_cocoa.h',
         'browser/ui/cocoa/screen_capture_notification_ui_cocoa.mm',
         'browser/ui/cocoa/speech_recognition_window_controller.h',
         'browser/ui/cocoa/speech_recognition_window_controller.mm',
@@ skipping 47 matching lines @@
         'browser/ui/cocoa/panels/panel_titlebar_view_cocoa.mm',
         'browser/ui/cocoa/panels/panel_window_controller_cocoa.h',
         'browser/ui/cocoa/panels/panel_window_controller_cocoa.mm',
       ],
       'mac_bundle_resources': [
         '<@(mac_all_xibs)',
       ],
     },  # target chrome_xibs
   ],  # targets
 }