Correct documentation for the location of MULTIPROCESS_TEST_MAIN()

Change-Id: I9e929ef2ac76d6bf5a30a538bc2bb84510eb1ea1
Reviewed-on: https://chromium-review.googlesource.com/c/1291629Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601459}

base/test/multiprocess_test.h

@@ -46,7 +46,7 @@ class CommandLine;
 //   }
 //
 //   // Note: |MULTIPROCESS_TEST_MAIN()| is defined in
-//   // testing/multi_process_function_list.h.
+//   // testing/multiprocess_func_list.h.
 //   MULTIPROCESS_TEST_MAIN(a_test_func) {
 //     // Code here runs in a child process....
 //     return 0;