Add Equals() to mojom structs and related types.

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

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_INTERNAL_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_INTERNAL_H_
 
 #include "mojo/public/cpp/bindings/lib/template_util.h"
 #include "mojo/public/cpp/bindings/struct_ptr.h"
 #include "mojo/public/cpp/system/core.h"
 
 namespace mojo {
 class String;
 
+template <typename T>
+class Array;
+
+template <typename K, typename V>
+class Map;
+
 namespace internal {
 template <typename T>
 class Array_Data;
 
 #pragma pack(push, 1)
 
 struct StructHeader {
   uint32_t num_bytes;
   uint32_t num_fields;
 };
@@ skipping 62 matching lines @@
 };
 template <typename S>
 struct WrapperTraits<InlinedStructPtr<S>, true> {
   typedef typename S::Data_* DataType;
 };
 template <typename S>
 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
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_INTERNAL_H_