Fire accessibility hover events when the touch exploration flag is set.

third_party/WebKit/public/web/WebAXEnums.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 28 matching lines @@
 enum WebAXEvent {
     WebAXEventActiveDescendantChanged,
     WebAXEventAlert,
     WebAXEventAriaAttributeChanged,
     WebAXEventAutocorrectionOccured,
     WebAXEventBlur,
     WebAXEventCheckedStateChanged,
     WebAXEventChildrenChanged,
     WebAXEventFocus,
     WebAXEventHide,
+    WebAXEventHover,
     WebAXEventInvalidStatusChanged,
     WebAXEventLayoutComplete,
     WebAXEventLiveRegionChanged,
     WebAXEventLoadComplete,
     WebAXEventLocationChanged,
     WebAXEventMenuListItemSelected,
     WebAXEventMenuListItemUnselected,
     WebAXEventMenuListValueChanged,
     WebAXEventRowCollapsed,
     WebAXEventRowCountChanged,
@@ skipping 229 matching lines @@
 // because on some platforms this determines how the accessible description
 // is exposed.
 enum WebAXDescriptionFrom {
     WebAXDescriptionFromPlaceholder,
     WebAXDescriptionFromRelatedElement
 };
 
 } // namespace blink
 
 #endif