Keep the split view activities topmost in z-order in Athena

athena/wm/window_manager_impl.h

Index: athena/wm/window_manager_impl.h
diff --git a/athena/wm/window_manager_impl.h b/athena/wm/window_manager_impl.h
index d741585ad7095cd268f5f12fb3aa4bc9d9f3da5d..b89557249f0d904ba0b93e9a8e9ec46732bdaab7 100644
--- a/athena/wm/window_manager_impl.h
+++ b/athena/wm/window_manager_impl.h
@@ -5,6 +5,7 @@
 #ifndef ATHENA_WM_WINDOW_MANAGER_IMPL_H_
 #define ATHENA_WM_WINDOW_MANAGER_IMPL_H_
 
+#include "athena/athena_export.h"
 #include "athena/input/public/accelerator_manager.h"
 #include "athena/wm/public/window_manager.h"
 #include "athena/wm/title_drag_controller.h"
@@ -29,11 +30,11 @@ class SplitViewController;
 class WindowListProvider;
 class WindowManagerObserver;
 
-class WindowManagerImpl : public WindowManager,
-                          public WindowOverviewModeDelegate,
-                          public aura::WindowObserver,
-                          public AcceleratorHandler,
-                          public TitleDragControllerDelegate {
+class ATHENA_EXPORT WindowManagerImpl : public WindowManager,
+                                        public WindowOverviewModeDelegate,
+                                        public aura::WindowObserver,
+                                        public AcceleratorHandler,
+                                        public TitleDragControllerDelegate {
  public:
   WindowManagerImpl();
   virtual ~WindowManagerImpl();
@@ -42,6 +43,8 @@ class WindowManagerImpl : public WindowManager,
   virtual void ToggleOverview() OVERRIDE;
   virtual bool IsOverviewModeActive() OVERRIDE;
 
+  void ToggleSplitView();
+
  private:
   friend class test::WindowManagerImplTestApi;
   friend class AthenaContainerLayoutManager;
@@ -54,8 +57,6 @@ class WindowManagerImpl : public WindowManager,
   // Sets whether overview mode is active.
   void SetInOverview(bool active);
 
-  void ToggleSplitview();
-
   void InstallAccelerators();
 
   // WindowManager: