[WIP] ash/extensions: Add experimental extension support for window-management in ash.

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index c6eb4d3773eaa1c164691ccd596b751986f9b65e..f3b7ff3ee101845416b3c32548db19cd1b68fc75 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 +453,16 @@ 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())
+      // TODO(sad): The delegate is leaking.
+      wm_extension->set_delegate(delegate_->CreateWindowManagerDelegate());
+  }
+
   // Initialize Primary RootWindow specific items.
   status_area_widget_ = new internal::StatusAreaWidget();
   status_area_widget_->CreateTrayViews(delegate_.get());