Add FrameStats default constructor

Bug 28592402

Change-Id: I857e46c9ab3ffae0d96923d665d13a4128a6cafa
diff --git a/include/ui/FrameStats.h b/include/ui/FrameStats.h
index 5fdf94d..6bfe635 100644
--- a/include/ui/FrameStats.h
+++ b/include/ui/FrameStats.h
@@ -25,6 +25,7 @@
 
 class FrameStats : public LightFlattenable<FrameStats> {
 public:
+    FrameStats() : refreshPeriodNano(0) {};
 
     /*
      * Approximate refresh time, in nanoseconds.