Pass sp<Fence>s around instead of file descriptors

Change-Id: Iac70584a2207940730e8f803a543e4e9a4000c47
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 1677c76..a4c613c 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -144,7 +144,7 @@
         HWComposer::HWCLayerInterface* layer) {
     if (layer) {
         layer->onDisplayed();
-        mSurfaceFlingerConsumer->setReleaseFence(layer->getAndResetReleaseFenceFd());
+        mSurfaceFlingerConsumer->setReleaseFence(layer->getAndResetReleaseFence());
     }
 }