Mojo C++ bindings: Fix bug: array<>, map<> should only initialize elements if they're not null when…

mojo/public/cpp/bindings/lib/map_serialization.h

Index: mojo/public/cpp/bindings/lib/map_serialization.h
diff --git a/mojo/public/cpp/bindings/lib/map_serialization.h b/mojo/public/cpp/bindings/lib/map_serialization.h
index f5939184b3eb9c958d240c3c71d6e7575ffcc452..98b5ff5972691fcfdf70631ecb8beb4324475cd0 100644
--- a/mojo/public/cpp/bindings/lib/map_serialization.h
+++ b/mojo/public/cpp/bindings/lib/map_serialization.h
@@ -68,7 +68,9 @@ struct MapSerializer<
     return count * sizeof(StructPointer<S_Data>);
   }
   static size_t GetItemSize(const S& item) {
-    return GetSerializedSize_(*UnwrapConstStructPtr<S>::value(item));
+    return !item.is_null()

[viettrungluu, 2015/12/07 22:03:51]

nit: Is S not testable? (I.e., would |return item ? ... : ...;| work instead?)

[vardhan, 2015/12/07 22:48:31]

Done.
It's testable.  I was trying to be more explicit about |item| not being a
pointer, but now realize that should be abstracted away.

+               ? GetSerializedSize_(*UnwrapConstStructPtr<S>::value(item))
+               : 0;
   }
 };