Add display task to trigger display configuration

ui/display/chromeos/display_util.h

+// Copyright 2014 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 UI_DISPLAY_CHROMEOS_DISPLAY_UTIL_H_
+#define UI_DISPLAY_CHROMEOS_DISPLAY_UTIL_H_
+
+#include <string>
+#include <vector>
+
+#include "ui/display/chromeos/display_configurator.h"
+#include "ui/display/types/display_constants.h"
+
+namespace ui {
+
+// Returns a string describing |state|.
+std::string DisplayPowerStateToString(chromeos::DisplayPowerState state);
+
+// Returns a string describing |state|.
+std::string MultipleDisplayStateToString(MultipleDisplayState state);
+
+// Returns the number of displays in |displays| that should be turned on, per
+// |state|.  If |display_power| is non-NULL, it is updated to contain the
+// on/off state of each corresponding entry in |displays|.
+int DISPLAY_EXPORT GetDisplayPower(
+    const std::vector<DisplayConfigurator::DisplayState>& display_states,
+    chromeos::DisplayPowerState state,
+    std::vector<bool>* display_power);
+
+}  // namespace ui
+
+#endif  // UI_DISPLAY_CHROMEOS_DISPLAY_UTIL_H_