Make sure constructors initialize all members

- Add default constructors to Parcelables that didn't have them and
  make sure all members are initialized by the constructors.
- Add missing fields to BufferItem flatten/unflatten.

Change-Id: I9aa83b326dc3aee757762e63be499dc96a74df91
diff --git a/include/ui/DisplayStatInfo.h b/include/ui/DisplayStatInfo.h
index 0549a83..09543ec 100644
--- a/include/ui/DisplayStatInfo.h
+++ b/include/ui/DisplayStatInfo.h
@@ -22,8 +22,8 @@
 namespace android {
 
 struct DisplayStatInfo {
-    nsecs_t vsyncTime;
-    nsecs_t vsyncPeriod;
+    nsecs_t vsyncTime{0};
+    nsecs_t vsyncPeriod{0};
 };
 
 }; // namespace android