Unify and change logout/sleep/lock shortcuts

ash/accelerators/exit_warning_handler.h

+// Copyright 2013 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 ASH_ACCELERATORS_EXIT_WARNING_HANDLER_H_
+#define ASH_ACCELERATORS_EXIT_WARNING_HANDLER_H_
+
+#include "ash/ash_export.h"
+#include "base/timer.h"
+
+namespace views {
+class Widget;
+}
+
+namespace ash {
+
+// In order to avoid accidental exits when the user presses the exit
+// shortcut by mistake, we require the user to hold the shortcut for
+// a period of time. During that time we show a popup informing the
+// user of this. We exit only if the user holds the shortcut longer
+// than this time limit.
+// An expert user may quickly release and then press again (double press)
+// for immediate exit. The press, release and press must happen within
+// the double press time limit.
+// If the user releases (without double press) before the required hold
+// time, we will cancel the exit, but show the ui until the hold time limit
+// has expired to avoid a short popup flash.
+//
+// State Transition Diagrams:
+//
+//  T1 - double press time limit (short)
+//  T2 - hold to exit time limit (long)
+//
+//  IDLE
+//   | Press
+//  WAIT_FOR_QUICK_RELEASE action: show ui & start timers
+//   | Release (DT < T1)
+//  WAIT_FOR_DOUBLE_PRESS
+//   | Press (DT < T1)
+//  EXITING action: hide ui, stop timers, exit
+//
+//  IDLE
+//   | Press
+//  WAIT_FOR_QUICK_RELEASE action: show ui & start timers
+//   | T1 timer expires
+//  WAIT_FOR_LONG_HOLD
+//   | T2 Timer exipres
+//  EXITING action: hide ui, exit
+//
+//  IDLE
+//   | Press
+//  WAIT_FOR_QUICK_RELEASE action: show ui & start timers
+//   | T1 timer expiers
+//  WAIT_FOR_LONG_HOLD
+//   | Release
+//  CANCELED
+//   | T2 timer expires
+//  IDLE action: hide ui
+//
+//  IDLE
+//   | Press
+//  WAIT_FOR_QUICK_RELEASE action: show ui & start timers
+//   | Release (DT < T1)
+//  WAIT_FOR_DOUBLE_PRESS
+//   | T1 timer expires
+//  CANCELED
+//   | T2 timer expires
+//  IDLE action: hide ui
+//
+
+class AcceleratorControllerTest;
+
+class ASH_EXPORT ExitWarningHandler {
+ public:
+  ExitWarningHandler();
+
+  ~ExitWarningHandler();
+
+  // Handles shortcut key press and release (Ctrl-Shift-Q).
+  void HandleExitKey(bool press);
+
+ private:
+  friend class AcceleratorControllerTest;
+
+  enum State {
+    IDLE,
+    WAIT_FOR_QUICK_RELEASE,
+    WAIT_FOR_DOUBLE_PRESS,
+    WAIT_FOR_LONG_HOLD,
+    CANCELED,
+    EXITING
+  };
+
+  // Performs actions (see state diagram above) when the "double key
+  // press" time limit is exceeded. This is the shorter of the two
+  // time limits.
+  void Timer1Action();
+
+  // Performs actions (see state diagram above) when the hold time
+  // limit is exceeded.  See state diagram above. This is the longer
+  // of the two time limits.
+  void Timer2Action();
+
+  void StartTimers();
+  void CancelTimers();
+
+  void Show();
+  void Hide();
+
+  State state_;
+  views::Widget* widget_; // owned by |this|.
+  base::OneShotTimer<ExitWarningHandler> timer1_; // short; double press
+  base::OneShotTimer<ExitWarningHandler> timer2_; // long; hold to exit
+
+  // Flag to suppress starting the timers for testing. For test we
+  // call TimerAction1() and TimerAction2() directly to simulate the
+  // expiration of the timers.
+  bool stub_timers_for_test_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExitWarningHandler);
+};
+
+}  // namespace ash
+
+#endif  // ASH_ACCELERATORS_EXIT_WARNING_HANDLER_H_
+