Rework FocusManager as FocusClient.

ui/aura/client/focus_client.h

+// 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 UI_AURA_CLIENT_FOCUS_CLIENT_H_
+#define UI_AURA_CLIENT_FOCUS_CLIENT_H_
+
+#include "ui/aura/aura_export.h"
+
+namespace ui {
+class Event;
+}
+
+namespace aura {
+class RootWindow;
+class Window;
+
+namespace client {
+class FocusChangeObserver;
+
+// An interface implemented by an object that manages window focus.
+class AURA_EXPORT FocusClient {
+ public:
+  virtual ~FocusClient() {}
+
+  // TODO(beng): these methods will be OBSOLETE by FocusChangeEvent.
+  virtual void AddObserver(FocusChangeObserver* observer) = 0;
+  virtual void RemoveObserver(FocusChangeObserver* observer) = 0;
+
+  // Focuses |window|. Passing NULL clears focus.
+  // TODO(beng): |event| may be obsolete.
+  virtual void FocusWindow(Window* window, const ui::Event* event) = 0;
+
+  // Retrieves the focused window, or NULL if there is none.
+  virtual Window* GetFocusedWindow() = 0;
+};
+
+// Sets/Gets the focus client on the RootWindow.
+AURA_EXPORT void SetFocusClient(RootWindow* root_window, FocusClient* client);
+AURA_EXPORT FocusClient* GetFocusClient(Window* window);
+AURA_EXPORT FocusClient* GetFocusClient(const Window* window);
+
+}  // namespace clients
+}  // namespace aura
+
+#endif  // UI_AURA_CLIENT_FOCUS_CLIENT_H_