Make GlobalDescriptors::MaybeGet return -1 when the key is not found.

testing/multiprocess_func_list.cc

Index: testing/multiprocess_func_list.cc
diff --git a/testing/multiprocess_func_list.cc b/testing/multiprocess_func_list.cc
index 1e19704830f37ba9778aeffd48dcb30d3ada4527..04c143d9e67f193d7c3a45bd657377b229e104d8 100644
--- a/testing/multiprocess_func_list.cc
+++ b/testing/multiprocess_func_list.cc
@@ -22,9 +22,13 @@ MultiProcessTestMap &GetMultiprocessFuncMap() {
 
 }  // namespace
 
-AppendMultiProcessTest::AppendMultiProcessTest(std::string test_name,
-                                               ChildFunctionPtr func_ptr) {
-  GetMultiprocessFuncMap()[test_name] = func_ptr;
+AppendMultiProcessTest::AppendMultiProcessTest(
+    std::string test_name,
+    ChildFunctionPtr main_func_ptr,
+    ChildFunctionPtr setup_func_ptr) {
+  if (setup_func_ptr)
+    (*setup_func_ptr)();
+  GetMultiprocessFuncMap()[test_name] = main_func_ptr;
 }
 
 int InvokeChildProcessTest(std::string test_name) {