[NOT FOR REVIEW] ash: Add some implementation for the window management extension API.

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index c6eb4d3773eaa1c164691ccd596b751986f9b65e..8fb3be0d0dbdf4f219dffb384728496cc65bb790 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -60,6 +60,7 @@
 #include "ash/wm/video_detector.h"
 #include "ash/wm/visibility_controller.h"
 #include "ash/wm/window_cycle_controller.h"
+#include "ash/wm/window_manager_extension.h"
 #include "ash/wm/window_modality_controller.h"
 #include "ash/wm/window_util.h"
 #include "ash/wm/window_properties.h"
@@ -452,6 +453,13 @@ void Shell::Init() {
 
   InitRootWindowController(root_window_controller);
 
+  // Note: This needs to happen after the root-window is initialized since it
+  // needs the activation-client.
+  internal::WindowManagerExtension* wm_extension =
+      new internal::WindowManagerExtension();
+  if (delegate_.get())
+    wm_extension->set_delegate(delegate_->CreateWindowManagerDelegate());
+
   // Initialize Primary RootWindow specific items.
   status_area_widget_ = new internal::StatusAreaWidget();
   status_area_widget_->CreateTrayViews(delegate_.get());