Check that the PNaCl cache hash is truly derived from the bitcode content.

chrome/renderer/pepper/ppb_nacl_hash_private_impl.h

+// Copyright (c) 2013 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.
+
+#ifndef CHROME_RENDERER_PEPPER_PPB_NACL_HASH_PRIVATE_IMPL_H_
+#define CHROME_RENDERER_PEPPER_PPB_NACL_HASH_PRIVATE_IMPL_H_
+
+#include "base/basictypes.h"
+#include "build/build_config.h"
+
+#ifndef DISABLE_NACL
+#include "ppapi/c/private/ppb_nacl_hash_private.h"
+
+class PPB_NaCl_Hash_Private_Impl {
+ public:
+  static const PPB_NaCl_Hash_Private* GetInterface();
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PPB_NaCl_Hash_Private_Impl);
+};
+
+#endif  // DISABLE_NACL
+
+#endif  // CHROME_RENDERER_PEPPER_PPB_NACL_HASH_PRIVATE_IMPL_H_