Rename function_ref_benchmark.cc into more generic function_type_benchmark.cc, add missing includes

PiperOrigin-RevId: 446209567
Change-Id: I9aac8ce10b93ed71f1260931995af1d32db6f780

absl/functional/BUILD.bazel

@@ -78,9 +78,9 @@ cc_test(
 )
 
 cc_test(
-    name = "function_ref_benchmark",
+    name = "function_type_benchmark",
     srcs = [
-        "function_ref_benchmark.cc",
+        "function_type_benchmark.cc",
     ],
     copts = ABSL_TEST_COPTS,
     tags = ["benchmark"],

absl/functional/function_type_benchmark.cc

@@ -1,4 +1,4 @@
-// Copyright 2019 The Abseil Authors.
+// Copyright 2022 The Abseil Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -12,12 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "absl/functional/function_ref.h"
-
+#include <functional>
 #include <memory>
+#include <string>
 
 #include "benchmark/benchmark.h"
 #include "absl/base/attributes.h"
+#include "absl/functional/function_ref.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN