diff -r 000000000000 -r 6474c204b198 content/xul/templates/src/nsTemplateMap.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/xul/templates/src/nsTemplateMap.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTemplateMap_h__
+#define nsTemplateMap_h__
+
+#include "pldhash.h"
+#include "nsXULElement.h"
+
+class nsTemplateMap {
+protected:
+    struct Entry {
+        PLDHashEntryHdr mHdr;
+        nsIContent*     mContent;
+        nsIContent*     mTemplate;
+    };
+
+    PLDHashTable mTable;
+
+    void
+    Init() { PL_DHashTableInit(&mTable, PL_DHashGetStubOps(), nullptr, sizeof(Entry), PL_DHASH_MIN_SIZE); }
+
+    void
+    Finish() { PL_DHashTableFinish(&mTable); }
+
+public:
+    nsTemplateMap() { Init(); }
+
+    ~nsTemplateMap() { Finish(); }
+
+    void
+    Put(nsIContent* aContent, nsIContent* aTemplate) {
+        NS_ASSERTION(PL_DHASH_ENTRY_IS_FREE(PL_DHashTableOperate(&mTable, aContent, PL_DHASH_LOOKUP)),
+                     "aContent already in map");
+
+        Entry* entry =
+            reinterpret_cast<Entry*>(PL_DHashTableOperate(&mTable, aContent, PL_DHASH_ADD));
+
+        if (entry) {
+            entry->mContent = aContent;
+            entry->mTemplate = aTemplate;
+        }
+    }
+
+    void
+    Remove(nsIContent* aContent) {
+        PL_DHashTableOperate(&mTable, aContent, PL_DHASH_REMOVE);
+
+        for (nsIContent* child = aContent->GetFirstChild();
+             child;
+             child = child->GetNextSibling()) {
+            Remove(child);
+        }
+    }
+
+
+    void
+    GetTemplateFor(nsIContent* aContent, nsIContent** aResult) {
+        Entry* entry =
+            reinterpret_cast<Entry*>(PL_DHashTableOperate(&mTable, aContent, PL_DHASH_LOOKUP));
+
+        if (PL_DHASH_ENTRY_IS_BUSY(&entry->mHdr))
+            NS_IF_ADDREF(*aResult = entry->mTemplate);
+        else
+            *aResult = nullptr;
+    }
+
+    void
+    Clear() { Finish(); Init(); }
+};
+
+#endif // nsTemplateMap_h__
+