1 files changed, 107 insertions, 0 deletions
diff --git a/ui/views/win/windows_session_change_observer.cc b/ui/views/win/windows_session_change_observer.cc
new file mode 100644
index 0000000..2b831f2
--- /dev/null
+++ b/ui/views/win/windows_session_change_observer.cc
@@ -0,0 +1,107 @@
+// Copyright 2015 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/win/windows_session_change_observer.h"
+
+#include <wtsapi32.h>
+#pragma comment(lib, "wtsapi32.lib")
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/singleton.h"
+#include "base/observer_list.h"
+#include "ui/gfx/win/singleton_hwnd.h"
+#include "ui/gfx/win/singleton_hwnd_observer.h"
+
+namespace views {
+
+class WindowsSessionChangeObserver::WtsRegistrationNotificationManager {
+ public:
+  static WtsRegistrationNotificationManager* GetInstance() {
+    return Singleton<WtsRegistrationNotificationManager>::get();
+  }
+
+  WtsRegistrationNotificationManager() {
+    AddSingletonHwndObserver();
+  }
+
+  ~WtsRegistrationNotificationManager() {
+    RemoveSingletonHwndObserver();
+  }
+
+  void AddObserver(WindowsSessionChangeObserver* observer) {
+    DCHECK(singleton_hwnd_observer_);
+    observer_list_.AddObserver(observer);
+  }
+
+  void RemoveObserver(WindowsSessionChangeObserver* observer) {
+    observer_list_.RemoveObserver(observer);
+  }
+
+ private:
+  friend struct DefaultSingletonTraits<WtsRegistrationNotificationManager>;
+
+  void OnWndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
+    switch (message) {
+      case WM_WTSSESSION_CHANGE:
+        FOR_EACH_OBSERVER(WindowsSessionChangeObserver,
+                          observer_list_,
+                          OnSessionChange(wparam));
+        break;
+      case WM_DESTROY:
+        RemoveSingletonHwndObserver();
+        break;
+    }
+  }
+
+  void AddSingletonHwndObserver() {
+    DCHECK(!singleton_hwnd_observer_);
+    singleton_hwnd_observer_.reset(new gfx::SingletonHwndObserver(
+        base::Bind(&WtsRegistrationNotificationManager::OnWndProc,
+                   base::Unretained(this))));
+    WTSRegisterSessionNotification(gfx::SingletonHwnd::GetInstance()->hwnd(),
+                                   NOTIFY_FOR_THIS_SESSION);
+  }
+
+  void RemoveSingletonHwndObserver() {
+    if (!singleton_hwnd_observer_)
+      return;
+
+    singleton_hwnd_observer_.reset(nullptr);
+    WTSUnRegisterSessionNotification(gfx::SingletonHwnd::GetInstance()->hwnd());
+    FOR_EACH_OBSERVER(WindowsSessionChangeObserver,
+                      observer_list_,
+                      ClearCallback());
+  }
+
+  ObserverList<WindowsSessionChangeObserver, true> observer_list_;
+  scoped_ptr<gfx::SingletonHwndObserver> singleton_hwnd_observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(WtsRegistrationNotificationManager);
+};
+
+WindowsSessionChangeObserver::WindowsSessionChangeObserver(
+    const WtsCallback& callback)
+    : callback_(callback) {
+  DCHECK(!callback_.is_null());
+  WtsRegistrationNotificationManager::GetInstance()->AddObserver(this);
+}
+
+WindowsSessionChangeObserver::~WindowsSessionChangeObserver() {
+  ClearCallback();
+}
+
+void WindowsSessionChangeObserver::OnSessionChange(WPARAM wparam) {
+  callback_.Run(wparam);
+}
+
+void WindowsSessionChangeObserver::ClearCallback() {
+  if (!callback_.is_null()) {
+    callback_.Reset();
+    WtsRegistrationNotificationManager::GetInstance()->RemoveObserver(this);
+  }
+}
+
+}  // namespace views