Validate MessageHeader before using

mojo/public/tests/test_support_private.h

Index: mojo/public/tests/test_support_private.h
diff --git a/mojo/public/tests/test_support_private.h b/mojo/public/tests/test_support_private.h
index 3674fec58677f21f858ae09de22d346b24d9f4ec..29983cad8cd898bdfb2b1b400c40c22a5d3dd57f 100644
--- a/mojo/public/tests/test_support_private.h
+++ b/mojo/public/tests/test_support_private.h
@@ -5,6 +5,8 @@
 #ifndef MOJO_PUBLIC_TESTS_TEST_SUPPORT_PRIVATE_H_
 #define MOJO_PUBLIC_TESTS_TEST_SUPPORT_PRIVATE_H_
 
+#include <stdio.h>
+
 #include "mojo/public/c/test_support/test_support.h"
 
 namespace mojo {
@@ -23,6 +25,9 @@ class MOJO_TEST_SUPPORT_EXPORT TestSupport {
   virtual void LogPerfResult(const char* test_name,
                              double value,
                              const char* units) = 0;
+  virtual FILE* OpenSourceRootRelativeFile(const char* relative_path) = 0;
+  virtual char** EnumerateSourceRootRelativeDirectory(
+      const char* relative_path) = 0;
 };
 
 }  // namespace test