Local NTP, Realbox: pressing Arrow up/down should reshow matches

Fixed: 1015685
Change-Id: Ie5241e62ccf06c854a578634cda968a55c21ea80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1867850
Auto-Submit: Dan Beam <dbeam@chromium.org>
Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Dan Beam <dbeam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707218}

chrome/browser/resources/local_ntp/local_ntp.js

@@ -1328,7 +1328,10 @@ function onRealboxWrapperKeydown(e) {
   }
 
   if (!areRealboxMatchesVisible()) {
-    // Only update output if matches are showing.
+    if (key === 'ArrowUp' || key === 'ArrowDown') {
+      setRealboxMatchesVisible(true);
+      e.preventDefault();
+    }
     return;
   }
 

chrome/test/data/local_ntp/realbox_browsertest.js

@@ -766,3 +766,40 @@ test.realbox.testPressEnterAfterFocusout = function() {
 
   assertTrue(clicked);
 };
+
+test.realbox.testArrowUpDownShowsMatchesWhenHidden = function() {
+  test.realbox.realboxEl.value = 'hello world';
+  test.realbox.realboxEl.dispatchEvent(new CustomEvent('input'));
+
+  chrome.embeddedSearch.searchBox.onqueryautocompletedone({
+    input: test.realbox.realboxEl.value,
+    matches: [test.realbox.getSearchMatch(), test.realbox.getUrlMatch()],
+  });
+
+  test.realbox.realboxEl.dispatchEvent(new Event('focusout', {
+    bubbles: true,
+    cancelable: true,
+    target: test.realbox.realboxEl,
+    relatedTarget: document.body,
+  }));
+
+  assertFalse(test.realbox.wrapperEl.classList.contains(
+      test.realbox.CLASSES.SHOW_MATCHES));
+
+  test.realbox.realboxEl.dispatchEvent(new Event('focusin', {
+    bubbles: true,
+    cancelable: true,
+    target: test.realbox.realboxEl,
+  }));
+
+  const arrowDown = new KeyboardEvent('keydown', {
+    bubbles: true,
+    cancelable: true,
+    key: 'ArrowDown',
+  });
+  test.realbox.realboxEl.dispatchEvent(arrowDown);
+  assertTrue(arrowDown.defaultPrevented);
+
+  assertTrue(test.realbox.wrapperEl.classList.contains(
+      test.realbox.CLASSES.SHOW_MATCHES));
+};