diff --git a/ash/shell/window_watcher.cc b/ash/shell/window_watcher.cc
new file mode 100644
index 0000000..05c4f74
--- /dev/null
+++ b/ash/shell/window_watcher.cc
@@ -0,0 +1,75 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ash/shell/window_watcher.h"
+
+#include "ash/launcher/launcher.h"
+#include "ash/launcher/launcher_model.h"
+#include "ash/shell.h"
+#include "ui/aura/window.h"
+
+namespace ash {
+namespace shell {
+
+WindowWatcher::WindowWatcher()
+    : window_(ash::Shell::GetInstance()->launcher()->window_container()) {
+  window_->AddObserver(this);
+}
+
+WindowWatcher::~WindowWatcher() {
+  window_->RemoveObserver(this);
+}
+
+aura::Window* WindowWatcher::GetWindowByID(ash::LauncherID id) {
+  IDToWindow::const_iterator i = id_to_window_.find(id);
+  return i != id_to_window_.end() ? i->second : NULL;
+}
+
+ash::LauncherID WindowWatcher::GetIDByWindow(aura::Window* window) const {
+  for (IDToWindow::const_iterator i = id_to_window_.begin();
+       i != id_to_window_.end(); ++i) {
+    if (i->second == window)
+      return i->first;
+  }
+  return 0;  // TODO: add a constant for this.
+}
+
+// aura::WindowObserver overrides:
+void WindowWatcher::OnWindowAdded(aura::Window* new_window) {
+  if (new_window->type() != aura::client::WINDOW_TYPE_NORMAL)
+    return;
+
+  static int image_count = 0;
+  ash::LauncherModel* model = ash::Shell::GetInstance()->launcher()->model();
+  ash::LauncherItem item;
+  item.type = ash::TYPE_TABBED;
+  id_to_window_[model->next_id()] = new_window;
+  item.num_tabs = image_count + 1;
+  item.image.setConfig(SkBitmap::kARGB_8888_Config, 16, 16);
+  item.image.allocPixels();
+  item.image.eraseARGB(255,
+                       image_count == 0 ? 255 : 0,
+                       image_count == 1 ? 255 : 0,
+                       image_count == 2 ? 255 : 0);
+  image_count = (image_count + 1) % 3;
+  model->Add(model->item_count(), item);
+}
+
+void WindowWatcher::OnWillRemoveWindow(aura::Window* window) {
+  for (IDToWindow::iterator i = id_to_window_.begin();
+       i != id_to_window_.end(); ++i) {
+    if (i->second == window) {
+      ash::LauncherModel* model =
+          ash::Shell::GetInstance()->launcher()->model();
+      int index = model->ItemIndexByID(i->first);
+      DCHECK_NE(-1, index);
+      model->RemoveItemAt(index);
+      id_to_window_.erase(i);
+      break;
+    }
+  }
+}
+
+}  // namespace shell
+}  // namespace ash