Move the concept of Activation to the Shell.

ui/aura_shell/default_container_event_filter.cc

Index: ui/aura_shell/default_container_event_filter.cc
===================================================================
--- ui/aura_shell/default_container_event_filter.cc	(revision 114022)
+++ ui/aura_shell/default_container_event_filter.cc	(working copy)
@@ -7,8 +7,8 @@
 #include "ui/aura/event.h"
 #include "ui/aura/window.h"
 #include "ui/aura_shell/default_container_layout_manager.h"
-#include "ui/aura_shell/stacking_controller.h"
 #include "ui/aura_shell/window_frame.h"
+#include "ui/aura_shell/window_util.h"
 #include "ui/base/hit_test.h"
 
 namespace {
@@ -77,7 +77,7 @@
       }
       break;
     case ui::ET_MOUSE_ENTERED:
-      UpdateHoveredWindow(StackingController::GetActivatableWindow(target));
+      UpdateHoveredWindow(GetActivatableWindow(target));
       break;
     case ui::ET_MOUSE_EXITED:
       UpdateHoveredWindow(NULL);