Fix UI glitches on Performance and Memory panels

third_party/WebKit/Source/devtools/front_end/timeline/TimelineTreeView.js

 // Copyright 2015 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.
 /**
  * @unrestricted
  */
 Timeline.TimelineTreeView = class extends UI.VBox {
   constructor() {
     super();
     this.element.classList.add('timeline-tree-view');
@@ skipping 14 matching lines @@
   /**
    * @param {!TimelineModel.TimelineModel} model
    * @param {!Array<!TimelineModel.TimelineModel.Filter>} filters
    */
   _init(model, filters) {
     this._model = model;
     this._linkifier = new Components.Linkifier();
 
     this._filters = filters.slice();
 
-    var columns = /** @type {!Array<!DataGrid.DataGrid.ColumnDescriptor>} */ ([]);
+    const columns = /** @type {!Array<!DataGrid.DataGrid.ColumnDescriptor>} */ ([]);
     this._populateColumns(columns);
 
-    var mainView = new UI.VBox();
+    this._splitWidget = new UI.SplitWidget(true, true, 'timelineTreeViewDetailsSplitWidget');
+    const mainView = new UI.VBox();
     this._populateToolbar(mainView.element);
+
     this._dataGrid = new DataGrid.SortableDataGrid(columns);
     this._dataGrid.addEventListener(DataGrid.DataGrid.Events.SortingChanged, this._sortingChanged, this);
     this._dataGrid.element.addEventListener('mousemove', this._onMouseMove.bind(this), true);
     this._dataGrid.setResizeMethod(DataGrid.DataGrid.ResizeMethod.Last);
     this._dataGrid.setRowContextMenuCallback(this._onContextMenu.bind(this));
     this._dataGrid.asWidget().show(mainView.element);
-
-    this._splitWidget = new UI.SplitWidget(true, true, 'timelineTreeViewDetailsSplitWidget');
-    this._splitWidget.show(this.element);
-    this._splitWidget.setMainWidget(mainView);
+    this._dataGrid.addEventListener(DataGrid.DataGrid.Events.SelectedNode, this._updateDetailsForSelection, this);
 
     this._detailsView = new UI.VBox();
     this._detailsView.element.classList.add('timeline-details-view', 'timeline-details-view-body');
+    this._splitWidget.setMainWidget(mainView);
     this._splitWidget.setSidebarWidget(this._detailsView);
-    this._dataGrid.addEventListener(DataGrid.DataGrid.Events.SelectedNode, this._updateDetailsForSelection, this);
+    this._splitWidget.hideSidebar();
+    this._splitWidget.show(this.element);
 
     /** @type {?TimelineModel.TimelineProfileTree.Node|undefined} */
     this._lastSelectedNode;
   }
 
   /**
    * @param {!Timeline.TimelineSelection} selection
    */
   updateContents(selection) {
     this.setRange(selection.startTime(), selection.endTime());
@@ skipping 491 matching lines @@
     }
     const groupBy = Timeline.AggregatedTimelineTreeView.GroupBy;
     addGroupingOption.call(this, Common.UIString('No Grouping'), groupBy.None);
     addGroupingOption.call(this, Common.UIString('Group by Activity'), groupBy.EventName);
     addGroupingOption.call(this, Common.UIString('Group by Category'), groupBy.Category);
     addGroupingOption.call(this, Common.UIString('Group by Domain'), groupBy.Domain);
     addGroupingOption.call(this, Common.UIString('Group by Subdomain'), groupBy.Subdomain);
     addGroupingOption.call(this, Common.UIString('Group by URL'), groupBy.URL);
     addGroupingOption.call(this, Common.UIString('Group by Frame'), groupBy.Frame);
     panelToolbar.appendToolbarItem(this._groupByCombobox);
+    panelToolbar.appendSpacer();
+    panelToolbar.appendToolbarItem(this._splitWidget.createShowHideSidebarButton(Common.UIString('heaviest stack')));
   }
 
   /**
    * @param {!TimelineModel.TimelineProfileTree.Node} treeNode
    * @return {!Array<!TimelineModel.TimelineProfileTree.Node>}
    */
   _buildHeaviestStack(treeNode) {
     console.assert(!!treeNode.parent, 'Attempt to build stack for tree root');
     var result = [];
     // Do not add root to the stack, as it's the tree itself.
@@ skipping 374 matching lines @@
 
   _onSelectionChanged() {
     this.dispatchEventToListeners(Timeline.TimelineStackView.Events.SelectionChanged);
   }
 };
 
 /** @enum {symbol} */
 Timeline.TimelineStackView.Events = {
   SelectionChanged: Symbol('SelectionChanged')
 };