DevTools: install resizer on horizontal headers in Sources.

third_party/WebKit/Source/devtools/front_end/sources/SourcesPanel.js

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 1027 matching lines @@
     if (this._threadsSidebarPane)
       this._sidebarPaneStack.showView(this._threadsSidebarPane);
 
     if (!vertically)
       this._sidebarPaneStack.appendView(this._watchSidebarPane);
 
     this._sidebarPaneStack.showView(this._callstackPane);
     var jsBreakpoints = /** @type {!UI.View} */ (UI.viewManager.view('sources.jsBreakpoints'));
     var scopeChainView = /** @type {!UI.View} */ (UI.viewManager.view('sources.scopeChain'));
 
+    if (this._tabbedLocationHeader) {
+      this._splitWidget.uninstallResizer(this._tabbedLocationHeader);
+      this._tabbedLocationHeader = null;
+    }
+
     if (!vertically) {
       // Populate the rest of the stack.
       this._sidebarPaneStack.showView(scopeChainView);
       this._sidebarPaneStack.showView(jsBreakpoints);
       this._extensionSidebarPanesContainer = this._sidebarPaneStack;
       this.sidebarPaneView = vbox;
+      this._splitWidget.uninstallResizer(this._debugToolbar.element);
     } else {
       var splitWidget = new UI.SplitWidget(true, true, 'sourcesPanelDebuggerSidebarSplitViewState', 0.5);
       splitWidget.setMainWidget(vbox);
 
       // Populate the left stack.
       this._sidebarPaneStack.showView(jsBreakpoints);
 
       var tabbedLocation = UI.viewManager.createTabbedLocation(this._revealDebuggerSidebar.bind(this));
       splitWidget.setSidebarWidget(tabbedLocation.tabbedPane());
+      this._tabbedLocationHeader = tabbedLocation.tabbedPane().headerElement();
+      this._splitWidget.installResizer(this._tabbedLocationHeader);
+      this._splitWidget.installResizer(this._debugToolbar.element);

[alph, 2017/05/23 21:23:07]

Is it ok to call this multiple times for _debugToolbar?

       tabbedLocation.appendView(scopeChainView);
       tabbedLocation.appendView(this._watchSidebarPane);
       this._extensionSidebarPanesContainer = tabbedLocation;
       this.sidebarPaneView = splitWidget;
     }
 
     this._sidebarPaneStack.appendApplicableItems('sources-sidebar');
     var extensionSidebarPanes = Extensions.extensionServer.sidebarPanes();
     for (var i = 0; i < extensionSidebarPanes.length; ++i)
       this._addExtensionSidebarPane(extensionSidebarPanes[i]);
@@ skipping 224 matching lines @@
    */
   willHide() {
     UI.inspectorView.setDrawerMinimized(false);
     setImmediate(() => Sources.SourcesPanel.updateResizerAndSidebarButtons(Sources.SourcesPanel.instance()));
   }
 
   _showViewInWrapper() {
     this._view.show(this.element);
   }
 };