Add xidle library to power_manager for testing how long the user has been idle

src/platform/power_manager/xidle.h

+// Copyright (c) 2009 The Chromium OS 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 SRC_PLATFORM_POWER_MANAGER_XIDLE_H_
+#define SRC_PLATFORM_POWER_MANAGER_XIDLE_H_
+
+#include <X11/extensions/scrnsaver.h>
+#include <X11/Xlib.h>
+#include "base/basictypes.h"
+
+namespace chromeos {
+
+// \brief Connect to the local X Server and determine how long the user has
+// been idle, in milliseconds.
+//
+// Creating a new XIdle object connects to the local X Server. When the object
+// is destroyed, the connection is also destroyed.
+//
+// \example
+// chromeos::XIdle idle;
+// uint64 idleTime;
+// if (idle.getIdleTime(&idleTime))
+//   std::cout << "User has been idle for " << idleTime << " milliseconds\n";
+// \end_example
+
+class XIdle {
+ public:
+  XIdle();
+  ~XIdle();
+
+  // Return how long the X Server has been idle, in milliseconds.
+  // If success, return true; otherwise return false.
+  bool getIdleTime(uint64 *idle);
+ private:
+  Display *display_;
+  XScreenSaverInfo *info_;
+  int event_base_, error_base_;
+  bool valid_;
+  DISALLOW_COPY_AND_ASSIGN(XIdle);
+};
+
+}  // namespace chromeos
+
+#endif  // SRC_PLATFORM_POWER_MANAGER_XIDLE_H_