Create a mirror window.

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 1e75bab37316800d9176672c764c33e318bf1c77..03477477433f4b610f14184530a851f8ff7dc5ae 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -16,6 +16,7 @@
 #include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/display/event_transformation_handler.h"
+#include "ash/display/mirror_window_controller.h"
 #include "ash/display/mouse_cursor_event_filter.h"
 #include "ash/display/screen_position_controller.h"
 #include "ash/drag_drop/drag_drop_controller.h"
@@ -298,6 +299,8 @@ Shell::~Shell() {
   power_button_controller_.reset();
   session_state_controller_.reset();
 
+  mirror_window_controller_.reset();
+
   // This also deletes all RootWindows. Note that we invoke Shutdown() on
   // DisplayController before resetting |display_controller_|, since destruction
   // of its owned RootWindowControllers relies on the value.
@@ -469,6 +472,8 @@ void Shell::Init() {
 
   screen_position_controller_.reset(new internal::ScreenPositionController);
   root_window_host_factory_.reset(delegate_->CreateRootWindowHostFactory());
+
+  mirror_window_controller_.reset(new internal::MirrorWindowController);
   display_controller_->Start();
   display_controller_->InitPrimaryDisplay();
   aura::RootWindow* root_window = display_controller_->GetPrimaryRootWindow();