Un-flake ChromeVoxBackgroundTest.ReadWindowTitle

This test attempted to wait for "foo" (the initial window title to be correctly read), however, we were getting
"  'Untitled - Chromium - User 1' properties={"category":"nav"}"
read out instead. This may indicate some races in the population of the window title under heavy load.

This wasn't the intent of the test though which covers only the reading of the title once it changes (from the initial value).

Removing this first expectation makes the test run without flaking.

Fixed: 1060001
Change-Id: I354f08c99299c315b980d15ab69fa11a0eddaa0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2111275Reviewed-by: Akihiro Ota <akihiroota@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751909}

chrome/browser/resources/chromeos/accessibility/chromevox/background/background_test.js

@@ -2457,7 +2457,6 @@ TEST_F('ChromeVoxBackgroundTest', 'ReadWindowTitle', function() {
     <p>start</p>
     <button id="click"></button>
     <script>
-      document.title = 'foo';
       const button = document.getElementById('click');
       button.addEventListener('click', _ => document.title = 'bar');
     </script>
@@ -2476,10 +2475,8 @@ TEST_F('ChromeVoxBackgroundTest', 'ReadWindowTitle', function() {
         };
 
         mockFeedback.clearPendingOutput()
-            .call(doCmd('readCurrentTitle'))
-            .expectSpeech(/^foo/)
             .call(clickButtonThenReadCurrentTitle)
-            .expectSpeech(/^bar/)
+            .expectSpeech(/^bar - Chromium*/)
             .replay();
       });
 });