Change behaviour of the Alt-] and Alt-[ keys so that it cycles through SnapLeft/SnapRight to DockLe…

ash/wm/dock/docked_window_layout_manager.h

Index: ash/wm/dock/docked_window_layout_manager.h
diff --git a/ash/wm/dock/docked_window_layout_manager.h b/ash/wm/dock/docked_window_layout_manager.h
index 174eeae6aa81ec5f37c8cb87401662a6ab52738c..58118f515a50409c93fd213ccc5065f6723ecfde 100644
--- a/ash/wm/dock/docked_window_layout_manager.h
+++ b/ash/wm/dock/docked_window_layout_manager.h
@@ -121,6 +121,10 @@ class ASH_EXPORT DockedWindowLayoutManager
   // Used to snap docked windows to the side of screen during drag.
   DockedAlignment CalculateAlignment() const;
 
+  void set_preferred_alignment(DockedAlignment preferred_alignment) {
+    preferred_alignment_ = preferred_alignment;
+  }
+
   // Returns true when a window can be docked. Windows cannot be docked at the
   // edge used by the shelf or the edge opposite from existing dock.
   bool CanDockWindow(aura::Window* window, DockedAlignment desired_alignment);
@@ -299,6 +303,9 @@ class ASH_EXPORT DockedWindowLayoutManager
   // Side of the screen that the dock is positioned at.
   DockedAlignment alignment_;
 
+  // The preferred alignment of the next window to be added to docked layout.
+  DockedAlignment preferred_alignment_;
+
   // The last active window. Used to maintain stacking order even if no windows
   // are currently focused.
   aura::Window* last_active_window_;