Pass sp<Fence>s around instead of file descriptors

Change-Id: Iac70584a2207940730e8f803a543e4e9a4000c47
diff --git a/services/surfaceflinger/DisplayHardware/DisplaySurface.h b/services/surfaceflinger/DisplayHardware/DisplaySurface.h
index 6445848..bc717a9 100644
--- a/services/surfaceflinger/DisplayHardware/DisplaySurface.h
+++ b/services/surfaceflinger/DisplayHardware/DisplaySurface.h
@@ -52,7 +52,7 @@
     // hardware composer and a release fence is available for the buffer.
     // Further operations on the buffer can be queued as long as they wait for
     // the fence to signal.
-    virtual void onFrameCommitted(int fenceFd) = 0;
+    virtual void onFrameCommitted(const sp<Fence>& fence) = 0;
 
     virtual void dump(String8& result) const = 0;