Add Equals() to mojom structs and related types.

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 df3c620f084d2d1558e263b271b16f99a28cc635..80ec18ab01f9951dfdeb7156aacf9d5d2a5d803c 100644
--- a/mojo/public/cpp/bindings/lib/bindings_internal.h
+++ b/mojo/public/cpp/bindings/lib/bindings_internal.h
@@ -12,6 +12,12 @@
 namespace mojo {
 class String;
 
+template <typename T>
+class Array;
+
+template <typename K, typename V>
+class Map;
+
 namespace internal {
 template <typename T>
 class Array_Data;
@@ -94,6 +100,50 @@ struct WrapperTraits<S, true> {
   typedef typename S::Data_* DataType;
 };
 
+template <typename T>
+struct ValueTraits {
+  static bool Equals(const T& a, const T& b) { return a == b; }
+};
+
+// TODO(aa): It would be cool to have IsSpecializationOf<> template helper, but
+// got lost in the goop when I tried.
+template <typename T>
+struct ValueTraits<Array<T>> {
+  static bool Equals(const Array<T>& a, const Array<T>& b) {
+    return a.Equals(b);
+  }
+};
+
+template <typename T, typename U>
+struct ValueTraits<Map<T, U>> {
+  static bool Equals(const Map<T, U>& a, const Map<T, U>& b) {
+    return a.Equals(b);
+  }
+};
+
+template <typename T>
+struct ValueTraits<StructPtr<T>> {
+  static bool Equals(const StructPtr<T>& a, const StructPtr<T>& b) {
+    return a.Equals(b);
+  }
+};
+
+template <typename T>
+struct ValueTraits<InlinedStructPtr<T>> {
+  static bool Equals(const InlinedStructPtr<T>& a,
+                     const InlinedStructPtr<T>& b) {
+    return a.Equals(b);
+  }
+};
+
+template <typename T>
+struct ValueTraits<ScopedHandleBase<T>> {
+  static bool Equals(const ScopedHandleBase<T>& a,
+                     const ScopedHandleBase<T>& b) {
+    return a.get().value() == b.get().value();
+  }
+};
+
 }  // namespace internal
 }  // namespace mojo