Local NTP, Realbox: fix another suggestion removal focusout bug

I accidentally missed a case (or merge conflicted or something) in which
we should be ignoring focusout when the user deletes the focused item.

This specific case reproduces with these steps:
0) Search for "what are carbs" (and execute search)
1) Type "what" into realbox on NTP afterward
2) Move focus to "what are carbs" result
3) Press Shift+Delete

I've added an assert() to ensure this doesn't happen again, and added a
test. I've also updated a test that was triggering the assert() because
it was differing from what the prod code actually does (there was a
comment admitting that).

Bug: 1002689
Change-Id: Ic534ba725931291c3c327a43ea52d65d27ae51a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1868092
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@{#707461}

chrome/browser/resources/local_ntp/local_ntp.js

@@ -1076,6 +1076,8 @@ function onAddCustomLinkDone(success) {
 
 /** @param {!DeleteAutocompleteMatchResult} result */
 function onDeleteAutocompleteMatch(result) {
+  assert(matchElBeingDeleted);
+
   if (!result.success) {
     matchElBeingDeleted = null;
     return;
@@ -1305,6 +1307,7 @@ function onRealboxWrapperKeydown(e) {
   if (key === 'Delete') {
     if (e.shiftKey && !e.altKey && !e.ctrlKey && !e.metaKey &&
         autocompleteMatches[selected].supportsDeletion) {
+      matchElBeingDeleted = matchEls[selected];
       window.chrome.embeddedSearch.searchBox.deleteAutocompleteMatch(selected);
       e.preventDefault();
     }

chrome/test/data/local_ntp/realbox_browsertest.js

@@ -518,17 +518,10 @@ test.realbox.testUnsupportedDeletion = function() {
   });
   test.realbox.realboxEl.dispatchEvent(keyEvent);
   assertFalse(keyEvent.defaultPrevented);
+  assertEquals(0, test.realbox.deletedLines.length);
 
   const matchesEl = $(test.realbox.IDS.REALBOX_MATCHES);
   assertFalse(matchesEl.classList.contains(test.realbox.CLASSES.REMOVABLE));
-
-  // The below 2 statements shouldn't really happen in updated code but isn't
-  // terrible idea to keep testing for now. This is because SupportsDeletion()
-  // is now propagated to the client, so we shouldn't allow users (via the UI)
-  // to attempt to delete non-deletable things.
-  chrome.embeddedSearch.searchBox.ondeleteautocompletematch(
-      {success: false, matches: []});
-  assertEquals(1, $(test.realbox.IDS.REALBOX_MATCHES).children.length);
 };
 
 test.realbox.testSupportedDeletion = function() {
@@ -566,6 +559,14 @@ test.realbox.testSupportedDeletion = function() {
   test.realbox.realboxEl.dispatchEvent(shiftDelete);
   assertTrue(shiftDelete.defaultPrevented);
 
+  // Pretend like the focused match gets removed from DOM when deleted.
+  matchesEl.children[1].dispatchEvent(new Event('focusout', {bubbles: true}));
+
+  // stopAutocomplete() should not be called if the focused match gets removed
+  // from the DOM (and focus gets dropped). There's explicit code in the
+  // focusout handler to deal with this case.
+  assertEquals(0, test.realbox.stops.length);
+
   assertEquals(1, test.realbox.deletedLines.length);
   assertEquals(1, test.realbox.deletedLines[0]);