Prefer 'unpinned' as a default view of mixed states

If we select several files some of which are pinned and some not, show
overall state as unpinned as it's less confusing.

BUG=chromium:875473

Change-Id: I2d1cfe6b901b39bf2f20a8d1c766c405df22c565
Reviewed-on: https://chromium-review.googlesource.com/c/1343467Reviewed-by: Sam McNally <sammc@chromium.org>
Commit-Queue: Sergei Datsenko <dats@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609606}

ui/file_manager/file_manager/foreground/js/file_manager_commands.js

@@ -1503,7 +1503,7 @@ CommandHandler.COMMANDS_['toggle-pinned'] = /** @type {Command} */ ({
     // flickering.
     if (actionsModel) {
       event.command.setHidden(actionsModel && !action);
-      event.command.checked = !!offlineNotNeededAction;
+      event.command.checked = !!offlineNotNeededAction && !saveForOfflineAction;
     }
   }
 });