Show focus ring only for navigational keys

Bug: 1008838
Change-Id: Id8ca2de0720fe6a7254291b18d5969c6174780da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1842551Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
Cr-Commit-Position: refs/heads/master@{#703375}

chrome/browser/resources/local_ntp/customize.js

@@ -1984,7 +1984,9 @@ customize.initCustomBackgrounds = function(showErrorNotification) {
     richerPicker.classList.add(customize.CLASSES.MOUSE_NAV);
   };
   richerPicker.onkeydown = function(event) {
-    richerPicker.classList.remove(customize.CLASSES.MOUSE_NAV);
+    if (Object.values(customize.KEYCODES).includes(event.keyCode)) {
+      richerPicker.classList.remove(customize.CLASSES.MOUSE_NAV);
+    }
 
     if (event.keyCode === customize.KEYCODES.BACKSPACE &&
         customize.richerPicker_selectedSubmenu.menu.id ===