Add ActivationChangeObserver, replacing kRootWindowActiveWindowKey

BUG=123160
TEST=no functional change. all test must pass.

Review URL: https://chromiumcodereview.appspot.com/10500006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@140340 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 36 insertions, 7 deletions

diff --git a/ui/aura/client/activation_change_observer.h b/ui/aura/client/activation_change_observer.h
new file mode 100644
index 0000000..bcaf900
--- /dev/null
+++ b/ui/aura/client/activation_change_observer.h
@@ -0,0 +1,31 @@
+// 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_ACTIVATION_CHANGE_OBSERVER_H_
+#define UI_AURA_CLIENT_ACTIVATION_CHANGE_OBSERVER_H_
+#pragma once
+
+#include "ui/aura/aura_export.h"
+
+namespace aura {
+class Window;
+
+namespace client {
+
+class AURA_EXPORT ActivationChangeObserver {
+ public:
+  // Called when |active| gains focus, or there is no active window
+  // (|active| is NULL in this case.) |old_active| refers to the
+  // previous active window or NULL if there was no previously active
+  // window.
+  virtual void OnWindowActivated(Window* active, Window* old_active) = 0;
+
+ protected:
+  virtual ~ActivationChangeObserver() {}
+};
+
+}  // namespace client
+}  // namespace aura
+
+#endif  // UI_AURA_CLIENT_ACTIVATION_CHANGE_OBSERVER_H_
diff --git a/ui/aura/client/activation_client.cc b/ui/aura/client/activation_client.cc
index e9a5838..9348eb4 100644
--- a/ui/aura/client/activation_client.cc
+++ b/ui/aura/client/activation_client.cc
@@ -14,7 +14,6 @@ DECLARE_EXPORTED_WINDOW_PROPERTY_TYPE(AURA_EXPORT, bool);
 namespace aura {
 namespace client {
 
-DEFINE_WINDOW_PROPERTY_KEY(Window*, kRootWindowActiveWindowKey, NULL);
 DEFINE_WINDOW_PROPERTY_KEY(
     ActivationClient*, kRootWindowActivationClientKey, NULL);
 DEFINE_WINDOW_PROPERTY_KEY(bool, kHideOnDeactivate, false);
diff --git a/ui/aura/client/activation_client.h b/ui/aura/client/activation_client.h
index 7996a05..2d221dc 100644
--- a/ui/aura/client/activation_client.h
+++ b/ui/aura/client/activation_client.h
@@ -10,15 +10,19 @@
 #include "ui/aura/window.h"
 
 namespace aura {
-
 class Event;
 class RootWindow;
 
 namespace client {
+class ActivationChangeObserver;
 
 // An interface implemented by an object that manages window activation.
 class AURA_EXPORT ActivationClient {
  public:
+  // Adds/Removes ActivationChangeObservers.
+  virtual void AddObserver(ActivationChangeObserver* observer) = 0;
+  virtual void RemoveObserver(ActivationChangeObserver* observer) = 0;
+
   // Activates |window|. If |window| is NULL, nothing happens.
   virtual void ActivateWindow(Window* window) = 0;
 
@@ -46,11 +50,6 @@ AURA_EXPORT void SetActivationClient(RootWindow* root_window,
                                      ActivationClient* client);
 AURA_EXPORT ActivationClient* GetActivationClient(RootWindow* root_window);
 
-// A property key to store what the client defines as the active window on the
-// RootWindow.
-AURA_EXPORT extern const WindowProperty<Window*>* const
-    kRootWindowActiveWindowKey;
-
 // Some types of transient window are only visible when active.
 // The transient parents of these windows may have visual appearance properties
 // that differ from transient parents that can be deactivated.