Hook up the FocusController behind a flag.

ui/views/corewm/activation_change_shim.cc

Index: ui/views/corewm/activation_change_shim.cc
===================================================================
--- ui/views/corewm/activation_change_shim.cc	(revision 0)
+++ ui/views/corewm/activation_change_shim.cc	(revision 0)
@@ -0,0 +1,48 @@
+// 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/views/corewm/activation_change_shim.h"
+
+#include "base/command_line.h"
+#include "ui/aura/window.h"
+#include "ui/base/events/event_target.h"
+#include "ui/views/corewm/corewm_switches.h"
+#include "ui/views/corewm/focus_change_event.h"
+
+namespace views {
+namespace corewm {
+namespace {
+bool UseFocusController() {
+  return CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kUseFocusController);
+}
+}
+
+ActivationChangeShim::ActivationChangeShim(ui::EventTarget* target)
+    : target_(target) {
+  if (UseFocusController() && target_)
+    target_->AddPreTargetHandler(this);
+}
+
+ActivationChangeShim::~ActivationChangeShim() {
+  if (UseFocusController() && target_)
+    target_->RemovePreTargetHandler(this);
+}
+
+void ActivationChangeShim::OnWindowActivated(aura::Window* active,
+                                             aura::Window* old_active) {
+}
+
+ui::EventResult ActivationChangeShim::OnEvent(ui::Event* event) {
+  if (event->type() == FocusChangeEvent::activation_changed_event_type()) {
+    DCHECK(UseFocusController());
+    FocusChangeEvent* fce = static_cast<FocusChangeEvent*>(event);
+    OnWindowActivated(static_cast<aura::Window*>(event->target()),
+                      static_cast<aura::Window*>(fce->last_focus()));
+  }
+  return EventHandler::OnEvent(event);
+}
+
+}  // namespace corewm
+}  // namespace views