Remove stops_event_propagation from Window, since it's broken.

Changes it to be implemented by the Aura client, via a new interface EventClient.
The client can determine whether or not a given window and its subtree can receive events.
I also cleaned up the way screen locking is entered/exited via the delegate, and some stuff in ash/shell.

http://crbug.com/119347
TEST=none
Review URL: https://chromiumcodereview.appspot.com/9788001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@128553 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/ash/shell/window_watcher.h b/ash/shell/window_watcher.h
new file mode 100644
index 0000000..d36a4c8
--- /dev/null
+++ b/ash/shell/window_watcher.h
@@ -0,0 +1,52 @@
+// 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.
+
+#ifndef ASH_SHELL_WINDOW_WATCHER_H_
+#define ASH_SHELL_WINDOW_WATCHER_H_
+#pragma once
+
+#include <map>
+
+#include "ash/launcher/launcher_types.h"
+#include "base/compiler_specific.h"
+#include "base/logging.h"
+#include "ui/aura/window_observer.h"
+
+namespace aura {
+class Window;
+}
+
+namespace ash {
+namespace shell {
+
+// WindowWatcher is responsible for listening for newly created windows and
+// creating items on the Launcher for them.
+class WindowWatcher : public aura::WindowObserver {
+ public:
+  WindowWatcher();
+  virtual ~WindowWatcher();
+
+  aura::Window* GetWindowByID(ash::LauncherID id);
+  ash::LauncherID GetIDByWindow(aura::Window* window) const;
+
+  // aura::WindowObserver overrides:
+  virtual void OnWindowAdded(aura::Window* new_window) OVERRIDE;
+  virtual void OnWillRemoveWindow(aura::Window* window) OVERRIDE;
+
+ private:
+  typedef std::map<ash::LauncherID, aura::Window*> IDToWindow;
+
+  // Window watching for newly created windows to be added to.
+  aura::Window* window_;
+
+  // Maps from window to the id we gave it.
+  IDToWindow id_to_window_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowWatcher);
+};
+
+}  // namespace shell
+}  // namespace ash
+
+#endif  // ASH_SHELL_WINDOW_WATCHER_H_