[quickview] Add openQuickViewTabIndexHtml test

Duplicate the openQuickViewTabIndexText test but here use an HTML file
as the preview file. This to document a difference between the preview
HTML and TEXT content renderers. The HTML renderer content is not part
of the tabindex order, while the TEXT renderer content *is*. Add a new
test to document the HTML renderer tabindex behavior.

Test: browser_tests --gtest_filter="*openQuickViewTabIndexHtml"
No-try: true
Bug: 1064855
Change-Id: Ieae14b0468c1142feeb23a240fb8f73c119bef4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2425605
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Alex Danilo <adanilo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809705}

chrome/browser/chromeos/file_manager/file_manager_browsertest.cc

@@ -521,6 +521,7 @@ WRAPPED_INSTANTIATE_TEST_SUITE_P(
         TestCase("openQuickViewMtp"),
         TestCase("openQuickViewTabIndexImage"),
         TestCase("openQuickViewTabIndexText"),
+        TestCase("openQuickViewTabIndexHtml"),
         TestCase("openQuickViewTabIndexAudio"),
         TestCase("openQuickViewTabIndexVideo"),
         TestCase("openQuickViewTabIndexDeleteDialog"),

ui/file_manager/integration_tests/file_manager/quick_view.js

@@ -2361,6 +2361,43 @@
     }
   };
 
+  /**
+   * Tests the tab-index focus order when sending tab keys when an HTML file is
+   * shown in Quick View.
+   */
+  testcase.openQuickViewTabIndexHtml = async () => {
+    // Prepare a list of tab-index focus queries.
+    const tabQueries = [
+      {'query': ['#quick-view', '[aria-label="Back"]:focus']},
+      {'query': ['#quick-view', '[aria-label="Open"]:focus']},
+      {'query': ['#quick-view', '[aria-label="Delete"]:focus']},
+      {'query': ['#quick-view', '[aria-label="File info"]:focus']},
+      {'query': ['#quick-view', '[aria-label="Back"]:focus']},
+    ];
+
+    // Open Files app on Downloads containing ENTRIES.tallHtml.
+    const appId = await setupAndWaitUntilReady(
+        RootPath.DOWNLOADS, [ENTRIES.tallHtml], []);
+
+    // Open the file in Quick View.
+    await openQuickView(appId, ENTRIES.tallHtml.nameText);
+
+    for (const query of tabQueries) {
+      // Make the browser dispatch a tab key event to FilesApp.
+      const result = await sendTestMessage(
+          {name: 'dispatchTabKey', shift: query.shift || false});
+      chrome.test.assertEq(
+          result, 'tabKeyDispatched', 'Tab key dispatch failure');
+
+      // Note: Allow 500ms between key events to filter out the focus
+      // traversal problems noted in crbug.com/907380#c10.
+      await wait(500);
+
+      // Check: the queried element should gain the focus.
+      await remoteCall.waitForElement(appId, query.query);
+    }
+  };
+
   /**
    * Tests the tab-index focus order when sending tab keys when an audio file is
    * shown in Quick View.