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..ec70d37716e05005da7d3f0fb9ada1b2d10cb052 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 +100,29 @@ struct WrapperTraits<S, true> {
   typedef typename S::Data_* DataType;
 };
 
+template <typename T, typename Enable = void>
+struct ValueTraits {
+  static bool Equals(const T& a, const T& b) { return a == b; }
+};
+
+template <typename T>
+struct ValueTraits<
+    T,
+    typename EnableIf<IsSpecializationOf<Array, T>::value ||
+                      IsSpecializationOf<Map, T>::value ||
+                      IsSpecializationOf<StructPtr, T>::value ||
+                      IsSpecializationOf<InlinedStructPtr, T>::value>::type> {
+  static bool Equals(const T& a, const 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