Add palette tray to ash.

ui/gfx/vector_icons_sources.gypi

 # Copyright 2016 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': {
     'common': [
       'vector_icons/account_box.icon',
       'vector_icons/account_child_invert.icon',
       'vector_icons/account_circle.icon',
@@ skipping 85 matching lines @@
       'vector_icons/omnibox_extension_app.1x.icon',
       'vector_icons/omnibox_extension_app.icon',
       'vector_icons/omnibox_http.icon',
       'vector_icons/omnibox_keyword_search.icon',
       'vector_icons/omnibox_search.icon',
       'vector_icons/omnibox_star.1x.icon',
       'vector_icons/omnibox_star.icon',
       'vector_icons/overflow_chevron.1x.icon',
       'vector_icons/overflow_chevron.icon',
       'vector_icons/paintbrush.icon',
+      'vector_icons/palette_tray_icon_default.1x.icon',
+      'vector_icons/palette_tray_icon_default.icon',
       'vector_icons/pdf.1x.icon',
       'vector_icons/pdf.icon',
       'vector_icons/photo_camera.icon',
       'vector_icons/protocol_handler.icon',
       'vector_icons/radio_button_active.icon',
       'vector_icons/radio_button_normal.icon',
       'vector_icons/remove_box.icon',
       'vector_icons/remove_circle.icon',
       'vector_icons/sad_tab.icon',
       'vector_icons/settings.icon',
@@ skipping 69 matching lines @@
       'vector_icons/window_control_minimize.icon',
       'vector_icons/window_control_restore.1x.icon',
       'vector_icons/window_control_restore.icon',
       'vector_icons/window_control_right_snapped.1x.icon',
       'vector_icons/window_control_right_snapped.icon',
       'vector_icons/zoom_minus.icon',
       'vector_icons/zoom_plus.icon',
     ],
   },
 }