Wait for display configuration to finish before suspending

ui/display/chromeos/display_configurator.cc

Index: ui/display/chromeos/display_configurator.cc
diff --git a/ui/display/chromeos/display_configurator.cc b/ui/display/chromeos/display_configurator.cc
index 0c7295451dc9b95c5069290ef6e33bd2a7f26130..151b8f1f331c617e3a5fb0b4f2ea2e2f174c9564 100644
--- a/ui/display/chromeos/display_configurator.cc
+++ b/ui/display/chromeos/display_configurator.cc
@@ -854,7 +854,8 @@ void DisplayConfigurator::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
-void DisplayConfigurator::SuspendDisplays() {
+void DisplayConfigurator::SuspendDisplays(
+    const ConfigurationCallback& callback) {
   // If the display is off due to user inactivity and there's only a single
   // internal display connected, switch to the all-on state before
   // suspending.  This shouldn't be very noticeable to the user since the
@@ -862,13 +863,14 @@ void DisplayConfigurator::SuspendDisplays() {
   // into the "on" state, which greatly reduces resume times.
   if (requested_power_state_ == chromeos::DISPLAY_POWER_ALL_OFF) {
     SetDisplayPower(chromeos::DISPLAY_POWER_ALL_ON,
-                    kSetDisplayPowerOnlyIfSingleInternalDisplay,
-                    base::Bind(&DoNothing));
+                    kSetDisplayPowerOnlyIfSingleInternalDisplay, callback);
 
     // 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.
     native_display_delegate_->SyncWithServer();
+  } else {
+    callback.Run(true);
   }
 
   displays_suspended_ = true;