Use vector assets for media router icons.

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 54 matching lines @@
       'vector_icons/location_bar_https_invalid.1x.icon',
       'vector_icons/location_bar_https_invalid.icon',
       'vector_icons/location_bar_https_valid.1x.icon',
       'vector_icons/location_bar_https_valid.icon',
       'vector_icons/location_bar_https_valid_in_chip.1x.icon',
       'vector_icons/location_bar_https_valid_in_chip.icon',
       'vector_icons/location_bar_star.icon',
       'vector_icons/location_bar_star_active.icon',
       'vector_icons/location_on.icon',
       'vector_icons/lock.icon',
+      'vector_icons/media_router_active.icon',
+      'vector_icons/media_router_error.icon',
+      'vector_icons/media_router_idle.icon',
+      'vector_icons/media_router_warning.icon',
       'vector_icons/menu_check.1x.icon',
       'vector_icons/menu_check.icon',
       'vector_icons/menu_radio_empty.icon',
       'vector_icons/menu_radio_selected.icon',
       'vector_icons/midi.icon',
       'vector_icons/mixed_content.icon',
       'vector_icons/mode_edit.icon',
       'vector_icons/my_location.icon',
       'vector_icons/navigate_back.1x.icon',
       'vector_icons/navigate_back.icon',
@@ skipping 101 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',
     ],
   },
 }