Validate MessageHeader before using

mojo/public/cpp/test_support/test_support.h

Index: mojo/public/cpp/test_support/test_support.h
diff --git a/mojo/public/cpp/test_support/test_support.h b/mojo/public/cpp/test_support/test_support.h
index d0a8eb8cfc0f272f6e2608d00e4d99a166e2bd2f..eb4d4be7116a7f3fac94b633702f60abafde628e 100644
--- a/mojo/public/cpp/test_support/test_support.h
+++ b/mojo/public/cpp/test_support/test_support.h
@@ -5,6 +5,9 @@
 #ifndef MOJO_PUBLIC_CPP_TEST_SUPPORT_TEST_SUPPORT_H_
 #define MOJO_PUBLIC_CPP_TEST_SUPPORT_TEST_SUPPORT_H_
 
+#include <string>
+#include <vector>
+
 #include "mojo/public/c/test_support/test_support.h"
 
 namespace mojo {
@@ -16,6 +19,15 @@ inline void LogPerfResult(const char* test_name,
   MojoTestSupportLogPerfResult(test_name, value, units);
 }
 
+// Opens text file relative to the source root for reading.
+inline FILE* OpenSourceRootRelativeFile(const std::string& relative_path) {
+  return MojoTestSupportOpenSourceRootRelativeFile(relative_path.c_str());
+}
+
+// Returns the list of regular files in a directory relative to the source root.
+std::vector<std::string> EnumerateSourceRootRelativeDirectory(
+    const std::string& relative_path);
+
 }  // namespace test
 }  // namespace mojo