[SyncFS] Add TaskLog tab on chrome://syncfs-internals

chrome/browser/resources/sync_file_system_internals/main.css

 /* Copyright 2013 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 * {
   font-family: Ubuntu, Arial, sans-serif;
 }
 
 tabbox {
   min-height: 650px;
@@ skipping 22 matching lines @@
 }
 
 .log-time {
   white-space: nowrap;
 }
 
 .log-event.error {
   background: rgb(255, 220, 220);
 }
 
+.task-log-details label {
+  cursor: pointer;
+}
+
+.task-log-collapse-check {
+  vertical-align: top;
+}
+
+.task-log-collapse-check ~ ul {
+  display: inline-block;
+  height: 1em;
+  list-style: none;
+  margin: 0;
+  overflow: hidden;
+  padding: 0;
+  position: relative;
+}
+
+.task-log-collapse-check:checked ~ ul {
+  height: auto;
+}
+
 .file-icon {
   background-image: url('chrome://syncfs-internals/file.png');
   background-position: 0 2px;
   background-repeat: no-repeat;
   padding-left: 18px;
 }
 
 .folder-icon {
   background-image: url('chrome://syncfs-internals/folder_closed.png');
   background-position: 0 2px;
   background-repeat: no-repeat;
   padding-left: 18px;
 }