CSRSS lockdown: destroy CSRSS heap

sandbox/win/src/heap_helper.h

Index: sandbox/win/src/heap_helper.h
diff --git a/sandbox/win/src/heap_helper.h b/sandbox/win/src/heap_helper.h
new file mode 100644
index 0000000000000000000000000000000000000000..3459b7d7f31c70573055a20e71d122594a01eeca
--- /dev/null
+++ b/sandbox/win/src/heap_helper.h
@@ -0,0 +1,21 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <windows.h>
+
+#include "base/win/windows_version.h"
+
+namespace sandbox {
+// These helper functions are not expected to be used generally, but are exposed
+// only to allow direct testing of this functionality.
+
+// Return the flags for this heap handle. Limited verification of the handle is
+// performed. No verification of the flags is performed.
+bool HeapFlags(HANDLE handle, DWORD* flags);
+
+// Return the handle to the CSR Port Heap, return nullptr if none or more than
+// one candidate was found.
+HANDLE FindCsrPortHeap();
+
+}  // namespace sandbox