Read compositor VSync information from platform, when possible

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 852b79419c1bf43d867e6edbe99da9ddaa54b2c1..0ffb8cc5fa0ec9088baefa650cdab4299736bc93 100644
--- a/chromeos/display/output_configurator.cc
+++ b/chromeos/display/output_configurator.cc
@@ -666,9 +666,10 @@ void OutputConfigurator::UpdateCachedOutputs() {
     OutputSnapshot* output = &cached_outputs_[i];
     if (output->has_display_id) {
       int width = 0, height = 0;
+      float refresh_rate;
       if (state_controller_ &&
           state_controller_->GetResolutionForDisplayId(
-              output->display_id, &width, &height)) {
+              output->display_id, &width, &height, &refresh_rate)) {
         output->selected_mode =
             FindOutputModeMatchingSize(*output, width, height);
       }