Fall back to X11 system tray icons if libappindicator is not available

chrome/browser/ui/libgtk2ui/libgtk2ui.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,
   },
   'targets': [
     {
@@ skipping 21 matching lines @@
         'LIBGTK2UI_IMPLEMENTATION',
       ],
       # Several of our source files are named _gtk2.cc. This isn't to
       # differentiate them from their source files (ninja and make are sane
       # build systems, unlike MSVS). It is instead to get around the rest of
       # the normal, global gtk exclusion rules, as we are otherwise using gtk
       # in a non-gtk build.
       'sources': [
         'app_indicator_icon.cc',
         'app_indicator_icon.h',
+        'app_indicator_icon_fallback.cc',
+        'app_indicator_icon_fallback.h',
+        'app_indicator_icon_menu.cc',
+        'app_indicator_icon_menu.h',
         'chrome_gtk_frame.cc',
         'chrome_gtk_frame.h',
         'chrome_gtk_menu_subclasses.cc',
         'chrome_gtk_menu_subclasses.h',
         'g_object_destructor_filo.cc',
         'g_object_destructor_filo.h',
         'gconf_listener.cc',
         'gconf_listener.h',
         'gtk2_border.cc',
         'gtk2_border.h',
@@ skipping 40 matching lines @@
           # G_DEFINE_TYPE automatically generates a *get_instance_private inline function after glib 2.37.
           # That's unused. Prevent to complain about it.
           'cflags': [
             '-Wno-unused-function',
           ],
         }],
       ],
     },
   ],
 }