Port event watcher ChromeVox tests.

BUG=371692

Review URL: https://codereview.chromium.org/595633002

Cr-Commit-Position: refs/heads/master@{#296259}

chrome/browser/resources/chromeos/chromevox/chromevox_tests.gypi

@@ -140,6 +140,7 @@
         'common/page_selection_test.unitjs',
         'common/selection_util_test.unitjs',
         'common/spannable_test.unitjs',
+        'chromevox/injected/event_watcher_test.unitjs',
         'chromevox/injected/live_regions_test.unitjs',
         'host/chrome/braille_display_manager_test.unitjs',
         'host/chrome/braille_input_handler_test.unitjs',

chrome/browser/resources/chromeos/chromevox/testing/chromevox_unittest_base.js

@@ -29,6 +29,13 @@ function ChromeVoxUnitTestBase() {}
 ChromeVoxUnitTestBase.prototype = {
   __proto__: testing.Test.prototype,
 
+  /** @override */
+  closureModuleDeps: [
+    'cvox.ChromeVoxTester',
+    'cvox.ChromeVoxUserCommands',
+    'cvox.SpokenListBuilder',
+  ],
+
   /** @override */
   browsePreload: DUMMY_URL,
 
@@ -140,6 +147,18 @@ ChromeVoxUnitTestBase.prototype = {
     return this; // for chaining.
   },
 
+  /**
+   * Asserts the TTS engine spoke a certain string. Clears the TTS buffer.
+   * @param {string} expectedText The expected text.
+   * @return {ChromeVoxUnitTestBase} this.
+   */
+  assertSpoken: function(expectedText) {
+    assertEquals(expectedText,
+                 cvox.ChromeVoxTester.testTts().getUtterancesAsString());
+    cvox.ChromeVoxTester.clearUtterances();
+    return this; // for chaining.
+  },
+
   /**
    * Asserts a list of utterances are in the correct queue mode.
    * @param {cvox.SpokenListBuilder|Array} expectedList A list
@@ -167,5 +186,32 @@ ChromeVoxUnitTestBase.prototype = {
       expectedText, expectedQueueMode, text, queueMode) {
     assertEquals(expectedQueueMode, queueMode);
     assertEquals(expectedText, text);
+  },
+
+  /**
+   * Focuses an element.
+   * @param {string} id The id of the element to focus.
+   * @return {ChromeVoxUnitTestBase} this.
+   */
+  setFocus: function(id) {
+    $(id).focus();
+    return this; // for chaining.
+  },
+
+  /**
+   * Executes a ChromeVox user command.
+   * @param {string} command The name of the command to run.
+   * @return {ChromeVoxUnitTestBase} this.
+   */
+  userCommand: function(command) {
+    cvox.ChromeVoxUserCommands.commands[command]();
+    return this; // for chaining.
+  },
+
+  /**
+   * @return {cvox.SpokenListBuilder} A new builder.
+   */
+  spokenList: function() {
+    return new cvox.SpokenListBuilder();
   }
 };