Implement support for monitor suspend.

chromeos/display/output_configurator.cc

Index: chromeos/display/output_configurator.cc
diff --git a/chromeos/display/output_configurator.cc b/chromeos/display/output_configurator.cc
index b6480ded1b4dc169182bbf23d90d976f33d50855..b6894062e6bce374ea178904fe4eaa968a1fa8e6 100644
--- a/chromeos/display/output_configurator.cc
+++ b/chromeos/display/output_configurator.cc
@@ -769,9 +769,9 @@ bool OutputConfigurator::Dispatch(const base::NativeEvent& event) {
   }
 
   // Sets the timer for NotifyOnDisplayChanged().  When an output state change
-  // is issued, several notifications chould arrive and NotifyOnDisplayChanged()
+  // is issued, several notifications should arrive and NotifyOnDisplayChanged()
   // should be called once for the last one.  The timer could lead at most a few
-  // handreds milliseconds of delay for the notification, but it would be
+  // hundreds of milliseconds of delay for the notification, but it would be
   // unrecognizable for users.
   if (notification_timer_.get()) {
     notification_timer_->Reset();
@@ -799,6 +799,17 @@ bool OutputConfigurator::IsInternalOutputName(const std::string& name) {
   return name.find(kInternal_LVDS) == 0 || name.find(kInternal_eDP) == 0;
 }
 
+void OutputConfigurator::SuspendDisplays() {
+  // Turn displays on before suspend. At this point, the backlight is off,
+  // so we turn on the internal display so that we can resume directly into
+  // "on" state. This greatly reduces resume times.
+  ScreenPowerSet(true, true);
+  // We need to make sure that the monitor configuration we just did actually
+  // completes before we return, because otherwise the X message could be
+  // racing with the HandleSuspendReadiness message.
+  XSync(base::MessagePumpAuraX11::GetDefaultXDisplay(), 0);
+}
+
 void OutputConfigurator::NotifyOnDisplayChanged() {
   notification_timer_.reset();
   FOR_EACH_OBSERVER(Observer, observers_, OnDisplayModeChanged());