Mojo C++ bindings: add StringTraits and ArrayTraits for STL types.

mojo/public/cpp/bindings/lib/array_traits_standard.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_ARRAY_TRAITS_STANDARD_H_
-#define MOJO_PUBLIC_CPP_BINDINGS_LIB_ARRAY_TRAITS_STANDARD_H_
-
-#include "mojo/public/cpp/bindings/array.h"
-#include "mojo/public/cpp/bindings/array_traits.h"
-
-namespace mojo {
-
-template <typename T>
-struct ArrayTraits<Array<T>> {
-  using Element = T;
-
-  static bool IsNull(const Array<T>& input) { return input.is_null(); }
-  static void SetToNull(Array<T>* output) { *output = nullptr; }
-
-  static size_t GetSize(const Array<T>& input) { return input.size(); }
-
-  static T* GetData(Array<T>& input) { return &input.front(); }
-
-  static const T* GetData(const Array<T>& input) { return &input.front(); }
-
-  static typename Array<T>::RefType GetAt(Array<T>& input, size_t index) {
-    return input[index];
-  }
-
-  static typename Array<T>::ConstRefType& GetAt(const Array<T>& input,
-                                                size_t index) {
-    return input[index];
-  }
-
-  static void Resize(Array<T>& input, size_t size) { input.resize(size); }
-};
-
-}  // namespace mojo
-
-#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_ARRAY_TRAITS_STANDARD_H_