Remove internal uses of mojo::Array and mojo::WTFArray.

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

 // Copyright 2016 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_HASH_UTIL_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_HASH_UTIL_H_
 
 #include <cstring>
 #include <functional>
 #include <type_traits>
 #include <vector>
 
+#include "base/optional.h"
 #include "mojo/public/cpp/bindings/lib/template_util.h"
 
 namespace mojo {
 namespace internal {
 
 template <typename T>
 size_t HashCombine(size_t seed, const T& value) {
   // Based on proposal in:
   // http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf
   return seed ^ (std::hash<T>()(value) + (seed << 6) + (seed >> 2));
@@ skipping 33 matching lines @@
 struct HashTraits<std::vector<T>, false> {
   static size_t Hash(size_t seed, const std::vector<T>& value) {
     for (const auto& element : value) {
       seed = HashCombine(seed, element);
     }
     return seed;
   }
 };
 
 template <typename T>
+struct HashTraits<base::Optional<std::vector<T>>, false> {
+  static size_t Hash(size_t seed, const base::Optional<std::vector<T>>& value) {
+    if (!value)
+      return HashCombine(seed, 0);
+
+    return Hash(seed, *value);
+  }
+};
+
+template <typename T>
 size_t Hash(size_t seed, const T& value) {
   return HashTraits<T>::Hash(seed, value);
 }
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_HASH_UTIL_H_