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

chrome/test/data/extensions/api_test/automation/tests/tabs/hit_test.js

+// Copyright 2017 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.
+
+var allTests = [
+  function testHitTest() {
+    var buttons = rootNode.findAll({ role: RoleType.BUTTON });
+    var button1 = buttons[0];
+    assertEq(button1.name, 'Hit Test 1');
+    var x = button1.location.left + button1.location.width / 2;
+    var y = button1.location.top + button1.location.height / 2;
+    var button2 = buttons[1];
+    assertEq(button2.name, 'Hit Test 2');
+    var webArea = button1.parent;
+    while (webArea.role != RoleType.ROOT_WEB_AREA)
+      webArea = webArea.parent;
+    button1.addEventListener(EventType.HOVER, function() {
+      x = button2.location.left + button2.location.width / 2;
+      y = button2.location.top + button2.location.height / 2;
+      button2.addEventListener(EventType.ALERT, function() {
+        chrome.test.succeed();
+      }, true);
+      webArea.hitTest(x, y, EventType.ALERT);
+    }, true);
+    webArea.hitTest(x, y, EventType.HOVER);
+  }
+];
+
+setUpAndRunTests(allTests, 'hit_test.html');