Fix queuing of display power state change requests

ui/display/chromeos/display_configurator.cc

 // 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.
 
 #include "ui/display/chromeos/display_configurator.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 826 matching lines @@
 }
 
 void DisplayConfigurator::PrepareForExit() {
   configure_display_ = false;
 }
 
 void DisplayConfigurator::SetDisplayPowerInternal(
     chromeos::DisplayPowerState power_state,
     int flags,
     const ConfigurationCallback& callback) {
+  // Only skip if the current power state is the same and the latest requested
+  // power state is the same. If |pending_power_state_ != current_power_state_|
+  // then there is a current task pending or the last configuration failed. In
+  // either case request a new configuration to make sure the state is
+  // consistent with the expectations.
   if (power_state == current_power_state_ &&
+      power_state == pending_power_state_ &&
       !(flags & kSetDisplayPowerForceProbe)) {
     callback.Run(true);
     return;
   }
 
   pending_power_state_ = power_state;
   has_pending_power_state_ = true;
   pending_power_flags_ = flags;
   queued_configuration_callbacks_.push_back(callback);
 
@@ skipping 295 matching lines @@
   last_virtual_display_id_ = max_display_id & 0xff;
 
   return true;
 }
 
 bool DisplayConfigurator::IsDisplayOn() const {
   return current_power_state_ != chromeos::DISPLAY_POWER_ALL_OFF;
 }
 
 }  // namespace ui