Rework FocusManager as FocusClient.

ui/aura/client/focus_client.cc

+// 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 "ui/aura/client/focus_client.h"
+
+#include "ui/aura/root_window.h"
+#include "ui/aura/window_property.h"
+
+DECLARE_EXPORTED_WINDOW_PROPERTY_TYPE(AURA_EXPORT, aura::Window*)
+DECLARE_WINDOW_PROPERTY_TYPE(aura::client::FocusClient*)
+
+namespace aura {
+namespace client {
+
+DEFINE_WINDOW_PROPERTY_KEY(FocusClient*, kRootWindowFocusClientKey, NULL);
+
+void SetFocusClient(RootWindow* root_window, FocusClient* client) {
+  root_window->SetProperty(kRootWindowFocusClientKey, client);
+}
+
+FocusClient* GetFocusClient(Window* window) {
+  return GetFocusClient(static_cast<const Window*>(window));
+}
+
+FocusClient* GetFocusClient(const Window* window) {
+  const RootWindow* root_window = window->GetRootWindow();
+  return root_window ?
+      root_window->GetProperty(kRootWindowFocusClientKey) : NULL;
+}
+
+}  // namespace client
+}  // namespace aura