SurfaceFLinger: rename outLayerId

 - Rename outId to outLayerId to reflect what the Id is.
 - Remove the default value and require it to be non-nullptr

Test: SF tests
Change-Id: Icdbbab4a84e9bd5982d274ee5bf522e36545855a
diff --git a/services/surfaceflinger/RefreshRateOverlay.cpp b/services/surfaceflinger/RefreshRateOverlay.cpp
index 99d061d..f676d5b 100644
--- a/services/surfaceflinger/RefreshRateOverlay.cpp
+++ b/services/surfaceflinger/RefreshRateOverlay.cpp
@@ -176,12 +176,13 @@
 }
 
 bool RefreshRateOverlay::createLayer() {
+    int32_t layerId;
     const status_t ret =
             mFlinger.createLayer(String8("RefreshRateOverlay"), mClient,
                                  SevenSegmentDrawer::getWidth(), SevenSegmentDrawer::getHeight(),
                                  PIXEL_FORMAT_RGBA_8888,
                                  ISurfaceComposerClient::eFXSurfaceBufferState, LayerMetadata(),
-                                 &mIBinder, &mGbp, nullptr);
+                                 &mIBinder, &mGbp, nullptr, &layerId);
     if (ret) {
         ALOGE("failed to create buffer state layer");
         return false;