diff -r 000000000000 -r 6474c204b198 memory/mozalloc/tests/TestVolatileBuffer.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/memory/mozalloc/tests/TestVolatileBuffer.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,144 @@
+/* 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 "TestHarness.h"
+#include "mozilla/VolatileBuffer.h"
+#include "mozilla/NullPtr.h"
+#include <string.h>
+
+#if defined(ANDROID)
+#include <fcntl.h>
+#include <linux/ashmem.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#elif defined(XP_DARWIN)
+#include <mach/mach.h>
+#endif
+
+using namespace mozilla;
+
+int main(int argc, char **argv)
+{
+  ScopedXPCOM xpcom("VolatileBufferTests");
+  if (xpcom.failed()) {
+    return 1;
+  }
+
+  RefPtr<VolatileBuffer> heapbuf = new VolatileBuffer();
+  if (!heapbuf || !heapbuf->Init(512)) {
+    fail("Failed to initialize VolatileBuffer");
+    return 1;
+  }
+
+  {
+    VolatileBufferPtr<char> ptr(heapbuf);
+    if (ptr.WasBufferPurged()) {
+      fail("Buffer was immediately purged after initialization");
+      return 1;
+    }
+
+    if (!ptr) {
+      fail("Didn't get a pointer");
+      return 1;
+    }
+  }
+
+  RefPtr<VolatileBuffer> buf = new VolatileBuffer();
+  if (!buf || !buf->Init(16384)) {
+    fail("Failed to initialize VolatileBuffer");
+    return 1;
+  }
+
+  const char teststr[] = "foobar";
+
+  {
+    VolatileBufferPtr<char> ptr(buf);
+    if (ptr.WasBufferPurged()) {
+      fail("Buffer should not be purged immediately after initialization");
+      return 1;
+    }
+
+    if (!ptr) {
+      fail("Didn't get a pointer");
+      return 1;
+    }
+
+    {
+      VolatileBufferPtr<char> ptr2(buf);
+      if (ptr2.WasBufferPurged()) {
+        fail("Failed to Lock buffer again while currently locked");
+        return 1;
+      }
+
+      if (!ptr2) {
+        fail("Didn't get a pointer on the second lock");
+        return 1;
+      }
+
+      strcpy(ptr2, teststr);
+    }
+  }
+
+  {
+    VolatileBufferPtr<char> ptr(buf);
+    if (ptr.WasBufferPurged()) {
+      fail("Buffer was immediately purged after unlock");
+      return 1;
+    }
+
+    if (strcmp(ptr, teststr)) {
+      fail("Buffer failed to retain data after unlock");
+      return 1;
+    }
+  }
+
+  // Test purging if we know how to
+#if defined(MOZ_WIDGET_GONK)
+  // This also works on Android, but we need root.
+  int fd = open("/" ASHMEM_NAME_DEF, O_RDWR);
+  if (fd < 0) {
+    fail("Failed to open ashmem device");
+    return 1;
+  }
+  if (ioctl(fd, ASHMEM_PURGE_ALL_CACHES, NULL) < 0) {
+    fail("Failed to purge ashmem caches");
+    return 1;
+  }
+#elif defined(XP_DARWIN)
+  int state;
+  vm_purgable_control(mach_task_self(), (vm_address_t)NULL,
+                      VM_PURGABLE_PURGE_ALL, &state);
+#else
+  return 0;
+#endif
+
+  if (!buf->NonHeapSizeOfExcludingThis()) {
+    fail("Buffer should not be allocated on heap");
+    return 1;
+  }
+
+  {
+    VolatileBufferPtr<char> ptr(buf);
+    if (!ptr.WasBufferPurged()) {
+      fail("Buffer should not be unpurged after forced purge");
+      return 1;
+    }
+
+    if (!strcmp(ptr, teststr)) {
+      fail("Purge did not actually purge data");
+      return 1;
+    }
+  }
+
+  {
+    VolatileBufferPtr<char> ptr(buf);
+    if (ptr.WasBufferPurged()) {
+      fail("Buffer still purged after lock");
+      return 1;
+    }
+  }
+
+  return 0;
+}