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

src/platform/power_manager/xidle.cc

+// 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.
+
+#include "power_manager/xidle.h"
+#include <X11/extensions/scrnsaver.h>
+#include <X11/Xlib.h>
+
+namespace chromeos {
+
+XIdle::XIdle() {
+  display_ = XOpenDisplay(NULL);
+  info_ = XScreenSaverAllocInfo();
+  valid_ = display_ &&
+           XScreenSaverQueryExtension(display_, &event_base_, &error_base_);
+}
+
+XIdle::~XIdle() {
+  if (info_)
+    XFree(info_);
+  if (display_)
+    XCloseDisplay(display_);
+}
+
+bool XIdle::getIdleTime(uint64 *idle) {
+  if (valid_ &&
+      XScreenSaverQueryInfo(display_, DefaultRootWindow(display_), info_)) {
+    *idle = info_->idle;
+    return true;
+  }
+  return false;
+}
+
+}  // namespace chromeos