Revert "Add test coverage for ChromeVox api"

This reverts commit d7d410b6.

Reason for revert: Test is crashing on linux-chromeos-dbg builder.
See crbug.com/799229 for details.

Original change's description:
> Add test coverage for ChromeVox api
> 
> Bug: 
> Change-Id: I8b4c002427f14426753e6a4ddc083e50a33cb985
> Reviewed-on: https://chromium-review.googlesource.com/847896
> Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
> Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#527035}

TBR=dtseng@chromium.org,aleventhal@chromium.org,katie@chromium.org

Change-Id: I73164ee8c477eff6878e59993f52168c552ed523
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/851075Reviewed-by: Greg Levin <glevin@chromium.org>
Commit-Queue: Greg Levin <glevin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#527098}

chrome/browser/chromeos/accessibility/spoken_feedback_browsertest.cc

@@ -673,47 +673,6 @@ IN_PROC_BROWSER_TEST_P(SpokenFeedbackTest, ChromeVoxNextTabRecovery) {
   }
 }
 
-IN_PROC_BROWSER_TEST_P(SpokenFeedbackTest, ChromeVoxApi) {
-  EnableChromeVox();
-
-  ui_test_utils::NavigateToURL(
-      browser(),
-      GURL("data:text/html;charset=utf-8,"
-           "<script>"
-           "  var output = [];"
-           "  document.addEventListener('chromeVoxLoaded', function() {"
-           "    output.push('load');"
-           "    cvox.Api.speak(output.join(' '));"
-           "  });"
-           "  document.addEventListener('chromeVoxUnloaded', function() {"
-           "    output.push('unload');"
-           "  });"
-           "</script>"));
-
-  // At this point, ChromeVox loads, followed by the page load which will fire a
-  // chromeVoxLoaded event. The page signals back with a 'load' utterance.
-  while (true) {
-    std::string utterance = speech_monitor_.GetNextUtterance();
-    if (utterance == "load")
-      break;
-  }
-
-  // Unload ChromeVox, which should trigger the chromeVoxUnloaded event.
-  AccessibilityManager::Get()->EnableSpokenFeedback(
-      false, ash::A11Y_NOTIFICATION_NONE);
-
-  // Re-enable ChromeVox here, and check all three events were seen by the
-  // page. Note this exercises a slightly different codepath. Dynamic after
-  // page load injection whereas before we tested on load injection.
-  AccessibilityManager::Get()->EnableSpokenFeedback(
-      true, ash::A11Y_NOTIFICATION_NONE);
-  while (true) {
-    std::string utterance = speech_monitor_.GetNextUtterance();
-    if (utterance == "load unload load")
-      break;
-  }
-}
-
 //
 // Spoken feedback tests that run only in guest mode.
 //