diff -r 000000000000 -r 6474c204b198 dom/quota/ArrayCluster.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/quota/ArrayCluster.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,106 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* 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 mozilla_dom_quota_arraycluster_h__
+#define mozilla_dom_quota_arraycluster_h__
+
+#include "mozilla/dom/quota/QuotaCommon.h"
+
+#include "Client.h"
+
+BEGIN_QUOTA_NAMESPACE
+
+template <class ValueType, uint32_t Length = Client::TYPE_MAX>
+class ArrayCluster
+{
+public:
+  ArrayCluster()
+  {
+    mArrays.AppendElements(Length);
+  }
+
+  nsTArray<ValueType>&
+  ArrayAt(uint32_t aIndex)
+  {
+    MOZ_ASSERT(aIndex < Length, "Bad index!");
+    return mArrays[aIndex];
+  }
+
+  nsTArray<ValueType>&
+  operator[](uint32_t aIndex)
+  {
+    return ArrayAt(aIndex);
+  }
+
+  bool
+  IsEmpty()
+  {
+    for (uint32_t index = 0; index < Length; index++) {
+      if (!mArrays[index].IsEmpty()) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  template <class T>
+  void
+  AppendElementsTo(uint32_t aIndex, nsTArray<T>& aArray)
+  {
+    NS_ASSERTION(aIndex < Length, "Bad index!");
+    aArray.AppendElements(mArrays[aIndex]);
+  }
+
+  template <class T>
+  void
+  AppendElementsTo(uint32_t aIndex, ArrayCluster<T, Length>& aArrayCluster)
+  {
+    NS_ASSERTION(aIndex < Length, "Bad index!");
+    aArrayCluster[aIndex].AppendElements(mArrays[aIndex]);
+  }
+
+  template <class T>
+  void
+  AppendElementsTo(nsTArray<T>& aArray)
+  {
+    for (uint32_t index = 0; index < Length; index++) {
+      aArray.AppendElements(mArrays[index]);
+    }
+  }
+
+  template<class T>
+  void
+  AppendElementsTo(ArrayCluster<T, Length>& aArrayCluster)
+  {
+    for (uint32_t index = 0; index < Length; index++) {
+      aArrayCluster[index].AppendElements(mArrays[index]);
+    }
+  }
+
+  template<class T>
+  void
+  SwapElements(ArrayCluster<T, Length>& aArrayCluster)
+  {
+    for (uint32_t index = 0; index < Length; index++) {
+      mArrays[index].SwapElements(aArrayCluster.mArrays[index]);
+    }
+  }
+
+  void
+  Clear()
+  {
+    for (uint32_t index = 0; index < Length; index++) {
+      mArrays[index].Clear();
+    }
+  }
+
+private:
+  nsAutoTArray<nsTArray<ValueType>, Length> mArrays;
+};
+
+END_QUOTA_NAMESPACE
+
+#endif // mozilla_dom_quota_arraycluster_h__