Update vendored deps

third_party/abseil-cpp/absl/functional/BUILD.gn

@@ -0,0 +1,26 @@
+# Copyright 2020 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//third_party/abseil-cpp/absl.gni")
+
+absl_source_set("bind_front") {
+  sources = [ "internal/front_binder.h" ]
+  public = [ "bind_front.h" ]
+  deps = [
+    "//third_party/abseil-cpp/absl/base:base_internal",
+    "//third_party/abseil-cpp/absl/container:compressed_tuple",
+    "//third_party/abseil-cpp/absl/meta:type_traits",
+    "//third_party/abseil-cpp/absl/utility",
+  ]
+}
+
+absl_source_set("function_ref") {
+  sources = [ "internal/function_ref.h" ]
+  public = [ "function_ref.h" ]
+  deps = [
+    "//third_party/abseil-cpp/absl/base:base_internal",
+    "//third_party/abseil-cpp/absl/base:core_headers",
+    "//third_party/abseil-cpp/absl/meta:type_traits",
+  ]
+}