Add displayservice.

This hidl service provides information about vsync and hotplug
to vendor services which is required by at least some camera
hal implementations.

Test: VtsFwkDisplayServiceV1_0TargetTest
Bug: 38311538
Change-Id: Ifc344c11ca4b3c8cebc6f0145f506d1aa774506d
diff --git a/services/displayservice/DisplayService.cpp b/services/displayservice/DisplayService.cpp
new file mode 100644
index 0000000..1699673
--- /dev/null
+++ b/services/displayservice/DisplayService.cpp
@@ -0,0 +1,18 @@
+#include <displayservice/DisplayService.h>
+#include <displayservice/DisplayEventReceiver.h>
+
+namespace android {
+namespace frameworks {
+namespace displayservice {
+namespace V1_0 {
+namespace implementation {
+
+Return<sp<IDisplayEventReceiver>> DisplayService::getEventReceiver() {
+    return new DisplayEventReceiver();
+}
+
+}  // namespace implementation
+}  // namespace V1_0
+}  // namespace displayservice
+}  // namespace frameworks
+}  // namespace android