DevTools: add entry points for command menu

third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js

Index: third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js b/third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js
index e3dff50bbfe3d674745788a93514f9130649fc04..f89c6ca6a2816bb951f18c843336338bc8b5d9de 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js
+++ b/third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js
@@ -489,10 +489,11 @@ UI.TabbedPane = class extends UI.VBox {
   }
 
   /**
-   * @param {string} text
+   * @param {!Element} element
    */
-  setPlaceholderText(text) {
-    this._noTabsMessage = text;
+  setPlaceholderElement(element) {
+    this._noTabsMessageElement = element;
+    element.classList.add('fill');

[pfeldman, 2017/03/28 00:59:35]

You should not add classes to provided elements - they might be incompatible
with the ones you set. Either defer to placeholder to position itself or
introduce intermediate container.

Overall, keeping it in light dom might be not the best idea - there is now no
way placeholders are consistent.

[luoe, 2017/04/22 00:07:03]

Consistency sounds great to me, I'll keep it in the shadow.

   }
 
   _innerUpdateTabElements() {
@@ -501,16 +502,12 @@ UI.TabbedPane = class extends UI.VBox {
 
     if (!this._tabs.length) {
       this._contentElement.classList.add('has-no-tabs');
-      if (this._noTabsMessage && !this._noTabsMessageElement) {
-        this._noTabsMessageElement = this._contentElement.createChild('div', 'tabbed-pane-placeholder fill');
-        this._noTabsMessageElement.textContent = this._noTabsMessage;
-      }
+      if (this._noTabsMessageElement)
+        this.element.appendChild(this._noTabsMessageElement);
     } else {
       this._contentElement.classList.remove('has-no-tabs');
-      if (this._noTabsMessageElement) {
+      if (this._noTabsMessageElement)
         this._noTabsMessageElement.remove();
-        delete this._noTabsMessageElement;
-      }
     }
 
     this._measureDropDownButton();