Allow Mojo structs as map keys

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

Index: mojo/public/cpp/bindings/lib/wtf_hash_util.h
diff --git a/mojo/public/cpp/bindings/lib/wtf_hash_util.h b/mojo/public/cpp/bindings/lib/wtf_hash_util.h
new file mode 100644
index 0000000000000000000000000000000000000000..c77bc8815107146e2cf7554d205bb010fe1b9b0e
--- /dev/null
+++ b/mojo/public/cpp/bindings/lib/wtf_hash_util.h
@@ -0,0 +1,97 @@
+// 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_WTF_HASH_UTIL_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_LIB_WTF_HASH_UTIL_H_
+
+#include <type_traits>
+
+#include "mojo/public/cpp/bindings/lib/hash_util.h"
+#include "mojo/public/cpp/bindings/struct_ptr.h"
+#include "third_party/WebKit/Source/wtf/HashFunctions.h"
+#include "third_party/WebKit/Source/wtf/text/StringHash.h"
+#include "third_party/WebKit/Source/wtf/text/WTFString.h"
+
+namespace mojo {
+namespace internal {
+
+template <>
+struct HashTraits<WTF::String, false> {
+  static size_t Hash(size_t seed, const WTF::String& value) {
+    return HashCombine(seed, WTF::StringHash::hash(value));
+  }
+};
+
+template <typename T>
+struct StructPtrHashFn {
+  static unsigned hash(const StructPtr<T>& value) {
+    return value.Hash(kHashSeed);
+  }
+  static bool equal(const StructPtr<T>& left, const StructPtr<T>& right) {
+    return left.Equals(right);
+  }
+  static const bool safeToCompareToEmptyOrDeleted = false;
+};
+
+template <typename T>
+struct InlinedStructPtrHashFn {
+  static unsigned hash(const InlinedStructPtr<T>& value) {
+    return value.Hash(kHashSeed);
+  }
+  static bool equal(const InlinedStructPtr<T>& left,
+                    const InlinedStructPtr<T>& right) {
+    return left.Equals(right);
+  }
+  static const bool safeToCompareToEmptyOrDeleted = false;
+};
+
+}  // namespace internal
+}  // namespace mojo
+
+namespace WTF {
+
+template <typename T>
+struct DefaultHash<mojo::StructPtr<T>> {
+  using Hash = mojo::internal::StructPtrHashFn<T>;
+};
+
+template <typename T>
+struct HashTraits<mojo::StructPtr<T>>
+    : public GenericHashTraits<mojo::StructPtr<T>> {
+  static const bool hasIsEmptyValueFunction = true;
+  static bool isEmptyValue(const mojo::StructPtr<T>& value) {
+    return value.is_null();
+  }
+  static void constructDeletedValue(mojo::StructPtr<T>& slot, bool) {
+    mojo::internal::StructPtrWTFHelper<T>::ConstructDeletedValue(slot);
+  }
+  static bool isDeletedValue(const mojo::StructPtr<T>& value) {
+    return mojo::internal::StructPtrWTFHelper<T>::ConstructDeletedValue(value);

[Sam McNally, 2016/09/22 05:40:51]

Wat?

[tibell, 2016/09/22 07:18:33]

Done.

+  }
+};
+
+template <typename T>
+struct DefaultHash<mojo::InlinedStructPtr<T>> {
+  using Hash = mojo::internal::InlinedStructPtrHashFn<T>;
+};
+
+template <typename T>
+struct HashTraits<mojo::InlinedStructPtr<T>>
+    : public GenericHashTraits<mojo::InlinedStructPtr<T>> {
+  static const bool hasIsEmptyValueFunction = true;
+  static bool isEmptyValue(const mojo::InlinedStructPtr<T>& value) {
+    return value.is_null();
+  }
+  static void constructDeletedValue(mojo::InlinedStructPtr<T>& slot, bool) {
+    mojo::internal::InlinedStructPtrWTFHelper<T>::ConstructDeletedValue(slot);
+  }
+  static bool isDeletedValue(const mojo::InlinedStructPtr<T>& value) {
+    return mojo::internal::InlinedStructPtrWTFHelper<T>::ConstructDeletedValue(

[Sam McNally, 2016/09/22 05:40:51]

Ditto.

[tibell, 2016/09/22 07:18:33]

Done.

+        value);
+  }
+};
+
+}  // namespace WTF
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_WTF_HASH_UTIL_H_