[DevTools] Implement dock to left.

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 cd88b43045d1e3103edc2848f308b13c6f6c3335..69061d702c60f3d6a4675fa3733319e12d3c89dc 100644
--- a/third_party/WebKit/Source/devtools/front_end/main/Main.js
+++ b/third_party/WebKit/Source/devtools/front_end/main/Main.js
@@ -699,16 +699,21 @@ Main.Main.MainMenuItem = class {
       var undock = new UI.ToolbarToggle(Common.UIString('Undock into separate window'), 'largeicon-undock');
       var bottom = new UI.ToolbarToggle(Common.UIString('Dock to bottom'), 'largeicon-dock-to-bottom');
       var right = new UI.ToolbarToggle(Common.UIString('Dock to right'), 'largeicon-dock-to-right');
+      var left = new UI.ToolbarToggle(Common.UIString('Dock to left'), 'largeicon-dock-to-left');
       undock.addEventListener(
           UI.ToolbarButton.Events.MouseUp, setDockSide.bind(null, Components.DockController.State.Undocked));
       bottom.addEventListener(
           UI.ToolbarButton.Events.MouseUp, setDockSide.bind(null, Components.DockController.State.DockedToBottom));
       right.addEventListener(
           UI.ToolbarButton.Events.MouseUp, setDockSide.bind(null, Components.DockController.State.DockedToRight));
+      left.addEventListener(
+          UI.ToolbarButton.Events.MouseUp, setDockSide.bind(null, Components.DockController.State.DockedToLeft));
       undock.setToggled(Components.dockController.dockSide() === Components.DockController.State.Undocked);
       bottom.setToggled(Components.dockController.dockSide() === Components.DockController.State.DockedToBottom);
       right.setToggled(Components.dockController.dockSide() === Components.DockController.State.DockedToRight);
+      left.setToggled(Components.dockController.dockSide() === Components.DockController.State.DockedToLeft);
       dockItemToolbar.appendToolbarItem(undock);
+      dockItemToolbar.appendToolbarItem(left);
       dockItemToolbar.appendToolbarItem(bottom);
       dockItemToolbar.appendToolbarItem(right);
       contextMenu.appendCustomItem(dockItemElement);