Mojo C++ bindings: support Arrays that contain Maps.

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

Index: mojo/public/cpp/bindings/lib/bindings_internal.h
diff --git a/mojo/public/cpp/bindings/lib/bindings_internal.h b/mojo/public/cpp/bindings/lib/bindings_internal.h
index f12be10ab62a16923d0d0d216c84deb08d1edbe2..78bd55a740b8ac0942b4a4cbd00d39d01d004b5d 100644
--- a/mojo/public/cpp/bindings/lib/bindings_internal.h
+++ b/mojo/public/cpp/bindings/lib/bindings_internal.h
@@ -10,6 +10,7 @@
 
 namespace mojo {
 class String;
+template <typename Key, typename Value> class Map;
 
 namespace internal {
 template <typename T> class Array_Data;
@@ -48,6 +49,14 @@ union StringPointer {
 };
 MOJO_COMPILE_ASSERT(sizeof(StringPointer) == 8, bad_sizeof_StringPointer);
 
+template <typename Key, typename Value>
+struct MapPointerPair {
+  ArrayPointer<Key> keys;
+  ArrayPointer<Value> values;
+};
+MOJO_COMPILE_ASSERT(sizeof(MapPointerPair<char, char>) == 16,
+                    bad_sizeof_MapPointerPair);
+
 #pragma pack(pop)
 
 template <typename T>
@@ -76,6 +85,12 @@ template <typename T> struct WrapperTraits<T, false> {
 template <typename H> struct WrapperTraits<ScopedHandleBase<H>, true> {
   typedef H DataType;
 };
+template <typename KeyWrapperType, typename ValueWrapperType>
+struct WrapperTraits<Map<KeyWrapperType, ValueWrapperType>, true> {
+  typedef MapPointerPair<
+      typename WrapperTraits<KeyWrapperType>::DataType,
+      typename WrapperTraits<ValueWrapperType>::DataType> DataType;
+};
 template <typename S> struct WrapperTraits<S, true> {
   typedef typename S::Data_* DataType;
 };