[DevTools] UI for blocked URLs.

Source/devtools/front_end/ui/toolbar.css

 /*
  * Copyright (c) 2014 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.
  */
 
 :host {
     flex: none;
     padding: 0 2px;
 }
@@ skipping 220 matching lines @@
     margin-right: 2px;
 }
 
 .toolbar-divider {
     background-color: #ccc;
     width: 1px;
     margin: 2px 4px;
     height: 17px;
 }
 
+.toolbar-space {
+    flex: auto;
+}
+
 .toolbar-group-label {
     margin-left: 5px;
     margin-right: 3px;
     color: #888;
 }
 
 /* Predefined items */
 
 .dock-toolbar-item.toggled-undocked .glyph,
 .dock-toolbar-item-undock .glyph {
@@ skipping 269 matching lines @@
 }
 
 button.playback-rate-button {
     width: auto;
     margin-right: 10px;
 }
 
 .layout-editor-toolbar-item .glyph {
     -webkit-mask-position: 0 -144px;
 }