Second try for

ui/aura/test/test_activation_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/test/test_activation_client.h"
 
+#include "ui/aura/client/activation_delegate.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 
 namespace aura {
 namespace test {
 
 ////////////////////////////////////////////////////////////////////////////////
 // TestActivationClient, public:
 
-TestActivationClient::TestActivationClient(RootWindow* root_window)
-    : active_window_(NULL) {
+TestActivationClient::TestActivationClient(RootWindow* root_window) {
   client::SetActivationClient(root_window, this);
 }
 
 TestActivationClient::~TestActivationClient() {
+  for (unsigned int i = 0; i < active_windows_.size(); ++i) {
+    active_windows_[i]->RemoveObserver(this);
+  }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // TestActivationClient, client::ActivationClient implementation:
 
 void TestActivationClient::ActivateWindow(Window* window) {
-  if (active_window_)
-    active_window_->RemoveObserver(this);
-  active_window_ = window;
-  active_window_->AddObserver(this);
+  Window *last_active = GetActiveWindow();
+  if (last_active == window)
+    return;
+
+  RemoveActiveWindow(window);
+  active_windows_.push_back(window);
+  window->AddObserver(this);
+  if (aura::client::GetActivationDelegate(window))
+    aura::client::GetActivationDelegate(window)->OnActivated();
+
+  if (last_active && aura::client::GetActivationDelegate(last_active))
+    aura::client::GetActivationDelegate(last_active)->OnLostActive();
+
 }
 
 void TestActivationClient::DeactivateWindow(Window* window) {
-  if (window == active_window_) {
-    if (active_window_)
-      active_window_->RemoveObserver(this);
-    active_window_ = NULL;
-  }
+  if (aura::client::GetActivationDelegate(window))
+    aura::client::GetActivationDelegate(window)->OnLostActive();
 }
 
 Window* TestActivationClient::GetActiveWindow() {
-  return active_window_;
+  if (active_windows_.empty())
+    return NULL;
+  return active_windows_.back();
 }
 
 bool TestActivationClient::CanFocusWindow(Window* window) const {
   return true;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // TestActivationClient, WindowObserver implementation:
 
 void TestActivationClient::OnWindowDestroyed(Window* window) {
-  if (window == active_window_) {
+  if (window == GetActiveWindow()) {
     window->RemoveObserver(this);
-    active_window_ = NULL;
+    active_windows_.pop_back();
+    Window* next_active = GetActiveWindow();
+    if (next_active && aura::client::GetActivationDelegate(next_active))
+      aura::client::GetActivationDelegate(next_active)->OnActivated();
+    return;
+  }
+
+  RemoveActiveWindow(window);
+}
+
+void TestActivationClient::RemoveActiveWindow(Window* window) {
+  for (unsigned int i = 0; i < active_windows_.size(); ++i) {
+    if (active_windows_[i] == window) {
+      active_windows_.erase(active_windows_.begin() + i);
+      window->RemoveObserver(this);
+      return;
+    }
   }
 }
 
 }  // namespace test
 }  // namespace aura