DevTools: TabbedLocations only materialize tabs when needed

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

Index: third_party/WebKit/Source/devtools/front_end/ui/InspectorView.js
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/InspectorView.js b/third_party/WebKit/Source/devtools/front_end/ui/InspectorView.js
index 51292fb948ea6522f66e0aad41934a33f9e05622..8015df791b528a59552ff6f6ace7ef0e6f32436b 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/InspectorView.js
+++ b/third_party/WebKit/Source/devtools/front_end/ui/InspectorView.js
@@ -43,18 +43,9 @@ UI.InspectorView = class extends UI.VBox {
     this._drawerSplitWidget.hideDefaultResizer();
     this._drawerSplitWidget.enableShowModeSaving();
     this._drawerSplitWidget.show(this.element);
-
-    // Create drawer tabbed pane.
-    this._drawerTabbedLocation =
-        UI.viewManager.createTabbedLocation(this._showDrawer.bind(this, false), 'drawer-view', true);
-    this._drawerTabbedLocation.enableMoreTabsButton();
-    this._drawerTabbedPane = this._drawerTabbedLocation.tabbedPane();
-    this._drawerTabbedPane.setMinimumSize(0, 27);
-    var closeDrawerButton = new UI.ToolbarButton(Common.UIString('Close drawer'), 'largeicon-delete');
-    closeDrawerButton.addEventListener(UI.ToolbarButton.Events.Click, this._closeDrawer, this);
-    this._drawerTabbedPane.rightToolbar().appendToolbarItem(closeDrawerButton);
-    this._drawerSplitWidget.installResizer(this._drawerTabbedPane.headerElement());
-    this._drawerSplitWidget.setSidebarWidget(this._drawerTabbedPane);
+    this._drawerBuilt = false;

[einbinder, 2017/01/07 11:51:59]

What is this used for?

+    if (this._drawerSplitWidget.showMode() === UI.SplitWidget.ShowMode.Both)
+      this._drawerLocation();
 
     // Create main area tabbed pane.
     this._tabbedLocation = UI.viewManager.createTabbedLocation(
@@ -110,7 +101,7 @@ UI.InspectorView = class extends UI.VBox {
    * @return {?UI.ViewLocation}
    */
   resolveLocation(locationName) {
-    return this._drawerTabbedLocation;
+    return this._drawerLocation();
   }
 
   createToolbars() {
@@ -182,15 +173,32 @@ UI.InspectorView = class extends UI.VBox {
     return /** @type {!UI.Panel} */ (UI.viewManager.materializedWidget(this._tabbedPane.selectedTabId || ''));
   }
 
+  _drawerLocation() {

[einbinder, 2017/01/07 11:51:59]

jsdoc @return

+    if (this._drawerTabbedLocation)
+      return this._drawerTabbedLocation;
+    this._drawerBuilt = true;
+    this._drawerTabbedLocation =

[einbinder, 2017/01/07 11:51:59]

jsdoc @type this in constructor

+        UI.viewManager.createTabbedLocation(this._showDrawer.bind(this, false), 'drawer-view', true);
+    this._drawerTabbedLocation.enableMoreTabsButton();
+    this._drawerTabbedPane = this._drawerTabbedLocation.tabbedPane();

[einbinder, 2017/01/07 11:51:59]

var drawerTabbedPane =

+    this._drawerTabbedPane.setMinimumSize(0, 27);
+    var closeDrawerButton = new UI.ToolbarButton(Common.UIString('Close drawer'), 'largeicon-delete');
+    closeDrawerButton.addEventListener(UI.ToolbarButton.Events.Click, this._closeDrawer, this);
+    this._drawerTabbedPane.rightToolbar().appendToolbarItem(closeDrawerButton);
+    this._drawerSplitWidget.installResizer(this._drawerTabbedPane.headerElement());
+    this._drawerSplitWidget.setSidebarWidget(this._drawerTabbedPane);
+    return this._drawerTabbedLocation;
+  }
+
   /**
    * @param {boolean} focus
    */
   _showDrawer(focus) {
-    if (this._drawerTabbedPane.isShowing())
+    if (this._drawerLocation().tabbedPane().isShowing())
       return;
     this._drawerSplitWidget.showBoth();
     if (focus)
-      this._focusRestorer = new UI.WidgetFocusRestorer(this._drawerTabbedPane);
+      this._focusRestorer = new UI.WidgetFocusRestorer(this._drawerLocation().tabbedPane());
     else
       this._focusRestorer = null;
   }
@@ -199,11 +207,11 @@ UI.InspectorView = class extends UI.VBox {
    * @return {boolean}
    */
   drawerVisible() {
-    return this._drawerTabbedPane.isShowing();
+    return this._drawerLocation().tabbedPane().isShowing();

[einbinder, 2017/01/07 11:51:59]

!!this._drawerTabbedLocation && this._drawerLocation().tabbedPane().isShowing()

   }
 
   _closeDrawer() {
-    if (!this._drawerTabbedPane.isShowing())
+    if (!this._drawerLocation().tabbedPane().isShowing())

[einbinder, 2017/01/07 11:51:59]

!!this._drawerTabbedLocation && this._drawerLocation().tabbedPane().isShowing()

       return;
     if (this._focusRestorer)
       this._focusRestorer.restore();