[NTP][Realbox] Allows realbox suggestions to be deleted using 'Enter' key

crrev.com/c/2206222 broke this behavior by making the outer <div>
focusable and preventing the inner <button> to which the click handler
is attached to from gaining focus.

This CL restores the original behavior by attaching the handlers to the
outer focusable container. It also simplifies the a11y setup by making
the outer container a real button and the inner container an unfocusable
div.

Bug: 1095549
Change-Id: Iacc1d5f673545cd25cc93965463d57d7447a7ff3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2264801
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Tommy Li <tommycli@chromium.org>
Auto-Submit: Moe Ahmadi <mahmadi@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782017}

chrome/browser/resources/local_ntp/local_ntp.js

@@ -1686,29 +1686,25 @@ function renderAutocompleteMatches(matches, suggestionGroupsMap) {
    * @param {!function()} callback
    */
   function createActionButton(callback) {
-    const icon = document.createElement('button');
+    const icon = document.createElement('div');
     icon.classList.add(CLASSES.REMOVE_ICON);
-    icon.tabIndex = -1;
-    icon.onmousedown = e => {
+    const action = document.createElement('button');
+    action.classList.add(CLASSES.REMOVE_MATCH);
+    action.appendChild(icon);
+    action.onmousedown = e => {
       e.preventDefault();  // Stops default browser action (focus)
     };
-    icon.onauxclick = e => {
+    action.onauxclick = e => {
       if (e.button == 1) {
         // Middle click on delete should just noop for now (matches omnibox).
         e.preventDefault();
       }
     };
-    icon.onclick = e => {
+    action.onclick = e => {
       callback();
       e.preventDefault();  // Stops default browser action (navigation)
     };
 
-    const action = document.createElement('div');
-
-    action.classList.add(CLASSES.REMOVE_MATCH);
-    action.tabIndex = 0;
-    action.setAttribute('role', 'button');
-    action.appendChild(icon);
     return action;
   }