diff -r 000000000000 -r 6474c204b198 xpcom/glue/nsMemory.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/glue/nsMemory.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,145 @@
+/* -*- 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 nsMemory_h__
+#define nsMemory_h__
+
+#include "nsXPCOM.h"
+
+class nsIMemory;
+
+#define NS_MEMORY_CONTRACTID "@mozilla.org/xpcom/memory-service;1"
+#define NS_MEMORY_CID                                \
+{ /* 30a04e40-38e7-11d4-8cf5-0060b0fc14a3 */         \
+    0x30a04e40,                                      \
+    0x38e7,                                          \
+    0x11d4,                                          \
+    {0x8c, 0xf5, 0x00, 0x60, 0xb0, 0xfc, 0x14, 0xa3} \
+}
+
+
+/**
+ * Static helper routines to manage memory. These routines allow easy access
+ * to xpcom's built-in (global) nsIMemory implementation, without needing
+ * to go through the service manager to get it. However this requires clients
+ * to link with the xpcom DLL. 
+ *
+ * This class is not threadsafe and is intented for use only on the main
+ * thread.
+ */
+class nsMemory
+{
+public:
+    static NS_HIDDEN_(void*) Alloc(size_t size)
+        { return NS_Alloc(size); }
+
+    static NS_HIDDEN_(void*) Realloc(void* ptr, size_t size)
+        { return NS_Realloc(ptr, size); }
+
+    static NS_HIDDEN_(void) Free(void* ptr)
+        { NS_Free(ptr); }
+
+    static NS_COM_GLUE nsresult   HeapMinimize(bool aImmediate);
+    static NS_COM_GLUE void*      Clone(const void* ptr, size_t size);
+    static NS_COM_GLUE nsIMemory* GetGlobalMemoryService();       // AddRefs
+};
+
+/** 
+ * Macro to free all elements of an XPCOM array of a given size using
+ * freeFunc, then frees the array itself using nsMemory::Free().  
+ *
+ * Note that this macro (and its wrappers) can be used to deallocate a
+ * partially- or completely-built array while unwinding an error
+ * condition inside the XPCOM routine that was going to return the
+ * array.  For this to work on a partially-built array, your code
+ * needs to be building the array from index 0 upwards, and simply
+ * pass the number of elements that have already been built (and thus
+ * need to be freed) as |size|.
+ *
+ * Thanks to <alecf@netscape.com> for suggesting this form, which
+ * allows the macro to be used with NS_RELEASE / NS_RELEASE_IF in
+ * addition to nsMemory::Free.
+ * 
+ * @param size      Number of elements in the array.  If not a constant, this 
+ *                  should be a int32_t.  Note that this means this macro 
+ *                  will not work if size >= 2^31.
+ * @param array     The array to be freed.
+ * @param freeFunc  The function or macro to be used to free it. 
+ *                  For arrays of nsISupports (or any class derived
+ *                  from it), NS_IF_RELEASE (or NS_RELEASE) should be
+ *                  passed as freeFunc.  For most (all?) other pointer
+ *                  types (including XPCOM strings and wstrings),
+ *                  nsMemory::Free should be used, since the
+ *                  shared-allocator (nsMemory) is what will have been
+ *                  used to allocate the memory.  
+ */
+#define NS_FREE_XPCOM_POINTER_ARRAY(size, array, freeFunc)                    \
+    PR_BEGIN_MACRO                                                            \
+        int32_t iter_ = int32_t(size);                                        \
+        while (--iter_ >= 0)                                                  \
+            freeFunc((array)[iter_]);                                         \
+        NS_Free((array));                                                     \
+    PR_END_MACRO
+
+// convenience macros for commonly used calls.  mmmmm.  syntactic sugar.
+
+/** 
+ * Macro to free arrays of non-refcounted objects allocated by the
+ * shared allocator (nsMemory) such as strings and wstrings.  A
+ * convenience wrapper around NS_FREE_XPCOM_POINTER_ARRAY.
+ *
+ * @param size      Number of elements in the array.  If not a constant, this 
+ *                  should be a int32_t.  Note that this means this macro 
+ *                  will not work if size >= 2^31.
+ * @param array     The array to be freed.
+ */
+#define NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(size, array)                    \
+    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_Free)
+
+/**
+ * Macro to free an array of pointers to nsISupports (or classes
+ * derived from it).  A convenience wrapper around
+ * NS_FREE_XPCOM_POINTER_ARRAY.
+ *
+ * Note that if you know that none of your nsISupports pointers are
+ * going to be 0, you can gain a bit of speed by calling
+ * NS_FREE_XPCOM_POINTER_ARRAY directly and using NS_RELEASE as your
+ * free function.
+ *
+ * @param size      Number of elements in the array.  If not a constant, this 
+ *                  should be a int32_t.  Note that this means this macro 
+ *                  will not work if size >= 2^31.
+ * @param array     The array to be freed.
+ */
+#define NS_FREE_XPCOM_ISUPPORTS_POINTER_ARRAY(size, array)                    \
+    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_IF_RELEASE)
+
+/**
+ * A macro, NS_ALIGNMENT_OF(t_) that determines the alignment
+ * requirements of a type.
+ */
+namespace mozilla {
+  template <class T>
+  struct AlignmentTestStruct
+  {
+    char c;
+    T t;
+  };
+}
+
+#define NS_ALIGNMENT_OF(t_) \
+  (sizeof(mozilla::AlignmentTestStruct<t_>) - sizeof(t_))
+
+/**
+ * An enumeration type used to represent a method of assignment.
+ */
+enum nsAssignmentType {
+    NS_ASSIGNMENT_COPY,   // copy by value
+    NS_ASSIGNMENT_DEPEND, // copy by reference
+    NS_ASSIGNMENT_ADOPT   // copy by reference (take ownership of resource)
+};
+
+#endif // nsMemory_h__
+