Expose media controls to accessibility

ui/accessibility/ax_enums.idl

 // Copyright 2014 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.
 
 // TODO(nektar): Migrate entire file to Mojoq.
 // These should be kept in sync with third_party/WebKit/public/web/WebAXEnums.h
 // until the Chromium and Blink trees are merged.
 [camel_case_enum_to_string=true] namespace ui {
 
   // For new entries to the following four enums, also add to
@@ skipping 27 matching lines @@
     focus,
     hide,                      // Remove: http://crbug.com/392502
     hover,
     image_frame_updated,       // Web
     invalid_status_changed,    // Implicit
     layout_complete,           // Web
     live_region_created,       // Implicit
     live_region_changed,       // Web
     load_complete,             // Web
     location_changed,          // Web
+    media_started_playing,     // Automation
+    media_stopped_playing,     // Automation
     menu_end,                  // Native / Win
     menu_list_item_selected,   // Web
     menu_list_value_changed,   // Web
     menu_popup_end,            // Native / Win
     menu_popup_start,          // Native / Win
     menu_start,                // Native / Win
     mouse_canceled,
     mouse_dragged,
     mouse_moved,
     mouse_pressed,
@@ skipping 560 matching lines @@
     // First node is before the second one.
     before,
 
     // Nodes are the same.
     equal,
 
     // First node is after the second one.
     after
   };
 };