Add DVR API for scroll event injection.

Bug: 62226675
Test: manual, vrcore build
Change-Id: Ic7d329eba8003b0e294b3a11a83ed5f868b801f8
diff --git a/services/vr/virtual_touchpad/DvrVirtualTouchpadClient.cpp b/services/vr/virtual_touchpad/DvrVirtualTouchpadClient.cpp
index eb152ed..3ab77a7 100644
--- a/services/vr/virtual_touchpad/DvrVirtualTouchpadClient.cpp
+++ b/services/vr/virtual_touchpad/DvrVirtualTouchpadClient.cpp
@@ -40,6 +40,11 @@
   return FromC(client)->ButtonState(touchpad, buttons);
 }
 
+int dvrVirtualTouchpadScroll(DvrVirtualTouchpad* client, int touchpad, float x,
+                             float y) {
+  return FromC(client)->Scroll(touchpad, x, y);
+}
+
 #ifdef __cplusplus
 }  // extern "C"
 #endif