Fix header guard for xfa_test_environment.h.

Change-Id: I9ab737f75a110f844f06f20d493715ba73494779
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/73575
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/testing/xfa_test_environment.h b/testing/xfa_test_environment.h
index efb9dd7..bbf3bdb 100644
--- a/testing/xfa_test_environment.h
+++ b/testing/xfa_test_environment.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef TESTING_XFA_UNIT_TEST_SUPPORT_H_
-#define TESTING_XFA_UNIT_TEST_SUPPORT_H_
+#ifndef TESTING_XFA_TEST_ENVIRONMENT_H_
+#define TESTING_XFA_TEST_ENVIRONMENT_H_
 
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -21,4 +21,4 @@
   void TearDown() override;
 };
 
-#endif  // TESTING_XFA_UNIT_TEST_SUPPORT_H_
+#endif  // TESTING_XFA_TEST_ENVIRONMENT_H_