ozone: Add overlay candidate implementation that queries support via IPC

ui/ozone/platform/drm/gpu/drm_window.cc

Index: ui/ozone/platform/drm/gpu/drm_window.cc
diff --git a/ui/ozone/platform/drm/gpu/drm_window.cc b/ui/ozone/platform/drm/gpu/drm_window.cc
index d71dea4bd37ca765cbc050497359377b8a3ac64e..6600d54fbf5f5b70189b49fc6eefe4c4c9da98bd 100644
--- a/ui/ozone/platform/drm/gpu/drm_window.cc
+++ b/ui/ozone/platform/drm/gpu/drm_window.cc
@@ -135,6 +135,12 @@ bool DrmWindow::SchedulePageFlip(bool is_sync, const base::Closure& callback) {
   return true;
 }
 
+bool DrmWindow::TestPageFlip(const OverlayPlaneList& planes) {
+  return controller_ &&
+         controller_->SchedulePageFlip(last_submitted_planes_, true, true,
+                                       base::Bind(&base::DoNothing));
+}
+
 const OverlayPlane* DrmWindow::GetLastModesetBuffer() {
   return OverlayPlane::GetPrimaryPlane(last_submitted_planes_);
 }