Generalize the HIT_TEST accessibility action so that it can send any event.

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 240 matching lines @@
 
     // Do the default action for an object, typically this means "click".
     do_default,
 
     focus,
 
     // Return the content of this image object in the image_data attribute.
     get_image_data,
 
     // Given a point, find the object it corresponds to and fire a
-    // HOVER event on it in response.
+    // |AXActionData.hit_test_event_to_fire| event on it in response.
     hit_test,
 
     // Increment a slider or range control by one step value.
     increment,
 
     // Delete any selected text in the control's text value and
     // insert |AXActionData::value| in its place, like when typing or pasting.
     replace_selected_text,
 
     // Scroll any scrollable containers to make the target object visible
@@ skipping 384 matching lines @@
     // First node is before the second one.
     before,
 
     // Nodes are the same.
     equal,
 
     // First node is after the second one.
     after
   };
 };