Reland of [DevTools] Show icon in top toolbar when Node target is available

third_party/WebKit/Source/devtools/front_end/main/Main.js

Index: third_party/WebKit/Source/devtools/front_end/main/Main.js
diff --git a/third_party/WebKit/Source/devtools/front_end/main/Main.js b/third_party/WebKit/Source/devtools/front_end/main/Main.js
index 576a84000cb50a297f9b98e9b061c7a5373d923c..22660ca2feab2f568064c53356f8347e40bb0849 100644
--- a/third_party/WebKit/Source/devtools/front_end/main/Main.js
+++ b/third_party/WebKit/Source/devtools/front_end/main/Main.js
@@ -728,6 +728,37 @@
   }
 };
 
+/**
+ * @implements {UI.ToolbarItem.Provider}
+ */
+Main.Main.NodeIndicator = class {
+  constructor() {
+    var element = createElement('div');
+    var shadowRoot = UI.createShadowRootWithCoreStyles(element, 'main/nodeIcon.css');
+    this._element = shadowRoot.createChild('div', 'node-icon');
+    element.addEventListener('click', () => InspectorFrontendHost.openNodeFrontend(), false);
+    this._button = new UI.ToolbarItem(element);
+    this._button.setTitle(Common.UIString('Open dedicated DevTools for Node.js'));
+    SDK.targetManager.addEventListener(SDK.TargetManager.Events.AvailableNodeTargetsChanged, this._update, this);
+    this._button.setVisible(false);
+    this._update();
+  }
+
+  _update() {
+    this._element.classList.toggle('inactive', !SDK.targetManager.availableNodeTargetsCount());
+    if (SDK.targetManager.availableNodeTargetsCount())
+      this._button.setVisible(true);
+  }
+
+  /**
+   * @override
+   * @return {?UI.ToolbarItem}
+   */
+  item() {
+    return this._button;
+  }
+};
+
 Main.NetworkPanelIndicator = class {
   constructor() {
     // TODO: we should not access network from other modules.