Add a tuple of name, local name for hashing custom element definitions.

third_party/WebKit/Source/core/dom/custom/CustomElementDescriptorHash.h

Index: third_party/WebKit/Source/core/dom/custom/CustomElementDescriptorHash.h
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElementDescriptorHash.h b/third_party/WebKit/Source/core/dom/custom/CustomElementDescriptorHash.h
new file mode 100644
index 0000000000000000000000000000000000000000..bfa71a4bd08f6782832ff5cf8f99d65e2e41b154
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElementDescriptorHash.h
@@ -0,0 +1,53 @@
+// 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 CustomElementDescriptorHash_h
+#define CustomElementDescriptorHash_h
+
+#include "core/dom/custom/CustomElementDescriptor.h"
+#include "wtf/HashFunctions.h"
+#include "wtf/HashTraits.h"
+#include "wtf/text/AtomicStringHash.h"
+
+namespace blink {
+
+struct CustomElementDescriptorHash {
+    STATIC_ONLY(CustomElementDescriptorHash);
+    static unsigned hash(const CustomElementDescriptor& descriptor)
+    {
+        return WTF::hashInts(
+            AtomicStringHash::hash(descriptor.name()),
+            AtomicStringHash::hash(descriptor.localName()));
+    }
+
+    static bool equal(
+        const CustomElementDescriptor& a,
+        const CustomElementDescriptor& b)
+    {
+        return a == b;
+    }
+
+    static const bool safeToCompareToEmptyOrDeleted = true;
+};
+
+} // namespace blink
+
+namespace WTF {
+
+template<>
+struct HashTraits<blink::CustomElementDescriptor>
+    : SimpleClassHashTraits<blink::CustomElementDescriptor> {
+    STATIC_ONLY(HashTraits);
+    static const bool emptyValueIsZero =
+        HashTraits<AtomicString>::emptyValueIsZero;
+};
+
+template<>
+struct DefaultHash<blink::CustomElementDescriptor> {
+    using Hash = blink::CustomElementDescriptorHash;
+};
+
+} // namespace WTF
+
+#endif // CustomElementDescriptorHash_h