diff -r 000000000000 -r 6474c204b198 xpcom/base/nsIMemory.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/base/nsIMemory.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,115 @@
+/* -*- 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/. */
+
+#include "nsISupports.idl"
+
+/**
+ *
+ * nsIMemory: interface to allocate and deallocate memory. Also provides
+ * for notifications in low-memory situations.
+ *
+ * The frozen exported symbols NS_Alloc, NS_Realloc, and NS_Free
+ * provide a more efficient way to access XPCOM memory allocation. Using
+ * those symbols is preferred to using the methods on this interface.
+ *
+ * A client that wishes to be notified of low memory situations (for
+ * example, because the client maintains a large memory cache that
+ * could be released when memory is tight) should register with the
+ * observer service (see nsIObserverService) using the topic 
+ * "memory-pressure". There are three specific types of notications 
+ * that can occur.  These types will be passed as the |aData| 
+ * parameter of the of the "memory-pressure" notification: 
+ * 
+ * "low-memory"
+ * This will be passed as the extra data when the pressure 
+ * observer is being asked to flush for low-memory conditions.
+ *
+ * "low-memory-ongoing"
+ * This will be passed when we continue to be in a low-memory
+ * condition and we want to flush caches and do other cheap
+ * forms of memory minimization, but heavy handed approaches like
+ * a GC are unlikely to succeed.
+ *
+ * "-no-forward"
+ * This is appended to the above two parameters when the resulting
+ * notification should not be forwarded to the child processes.
+ *
+ * "heap-minimize"
+ * This will be passed as the extra data when the pressure 
+ * observer is being asked to flush because of a heap minimize 
+ * call.
+ *
+ * "alloc-failure"
+ * This will be passed as the extra data when the pressure 
+ * observer has been asked to flush because a malloc() or 
+ * realloc() has failed.
+ */
+
+[scriptable, uuid(6aef11c4-8615-44a6-9711-98f43805693d)]
+interface nsIMemory : nsISupports
+{
+    /**
+     * Allocates a block of memory of a particular size. If the memory 
+     * cannot be allocated (because of an out-of-memory condition), the
+     * process aborts.
+     *
+     * @param size - the size of the block to allocate
+     * @result the block of memory
+     */
+    [noscript, notxpcom] voidPtr alloc(in size_t size);
+
+    /**
+     * Reallocates a block of memory to a new size.
+     *
+     * @param ptr - the block of memory to reallocate
+     * @param size - the new size
+     * @result the reallocated block of memory
+     *
+     * If ptr is null, this function behaves like malloc.
+     * If s is the size of the block to which ptr points, the first
+     * min(s, size) bytes of ptr's block are copied to the new block.
+     * If the allocation succeeds, ptr is freed and a pointer to the 
+     * new block returned.  If the allocation fails, the process aborts.
+     */
+    [noscript, notxpcom] voidPtr realloc(in voidPtr ptr,
+                                         in size_t newSize);
+
+    /**
+     * Frees a block of memory. Null is a permissible value, in which case
+     * nothing happens. 
+     *
+     * @param ptr - the block of memory to free
+     */
+    [noscript, notxpcom] void free(in voidPtr ptr);
+
+    /**
+     * Attempts to shrink the heap.
+     * @param immediate - if true, heap minimization will occur
+     *   immediately if the call was made on the main thread. If
+     *   false, the flush will be scheduled to happen when the app is
+     *   idle.
+     * @throws NS_ERROR_FAILURE if 'immediate' is set an the call
+     *   was not on the application's main thread.
+     */
+    void heapMinimize(in boolean immediate);
+
+    /**
+     * This predicate can be used to determine if we're in a low-memory
+     * situation (what constitutes low-memory is platform dependent). This
+     * can be used to trigger the memory pressure observers.
+     *
+     * DEPRECATED - Always returns false.  See bug 592308.
+     */
+    boolean isLowMemory();
+
+    /**
+     * This predicate can be used to determine if the platform is a "low-memory"
+     * platform. Callers may use this to dynamically tune their behaviour
+     * to favour reduced memory usage at the expense of performance. The value
+     * returned by this function will not change over the lifetime of the process.
+     */
+    boolean isLowMemoryPlatform();
+};
+