Mojo C++ bindings: add a new mode to generator to use native STL/WTF types

mojo/public/cpp/bindings/array_traits_stl.h

Index: mojo/public/cpp/bindings/array_traits_stl.h
diff --git a/mojo/public/cpp/bindings/array_traits_stl.h b/mojo/public/cpp/bindings/array_traits_stl.h
index 51af5ad7a1b28dae51c5b4f77d449b0a115761c5..9054a920190cd455890b3263e366c1811b3ce574 100644
--- a/mojo/public/cpp/bindings/array_traits_stl.h
+++ b/mojo/public/cpp/bindings/array_traits_stl.h
@@ -43,7 +43,16 @@ struct ArrayTraits<std::vector<T>> {
   }
 
   static bool Resize(std::vector<T>& input, size_t size) {
-    input.resize(size);
+    if (input.size() != size) {
+      // This is a hack to make compilers for Mac and Android happy. They
+      // currently don't allow resizing types like
+      // std::vector<std::vector<MoveOnlyType>>.
+      // Because the deserialization code doesn't care about the original
+      // contents of |input|, we discard them directly.
+      std::vector<T> temp(size);
+      input.swap(temp);
+    }
+
     return true;
   }
 };