initial version of the headless download manager delegate

headless/BUILD.gn

Index: headless/BUILD.gn
diff --git a/headless/BUILD.gn b/headless/BUILD.gn
index a038ce3cf09daefa81ad761cf81db79ace9f7a35..8c75dcf6fd5863688190f76ecc8e07cf4df65371 100644
--- a/headless/BUILD.gn
+++ b/headless/BUILD.gn
@@ -235,6 +235,8 @@ component("headless") {
     "lib/browser/headless_devtools_client_impl.h",
     "lib/browser/headless_devtools_manager_delegate.cc",
     "lib/browser/headless_devtools_manager_delegate.h",
+    "lib/browser/headless_download_manager_delegate.cc",
+    "lib/browser/headless_download_manager_delegate.h",
     "lib/browser/headless_net_log.cc",
     "lib/browser/headless_net_log.h",
     "lib/browser/headless_network_delegate.cc",
@@ -511,6 +513,7 @@ test("headless_browsertests") {
     "lib/headless_browser_browsertest.cc",
     "lib/headless_browser_context_browsertest.cc",
     "lib/headless_devtools_client_browsertest.cc",
+    "lib/headless_download_browsertest.cc",
     "lib/headless_web_contents_browsertest.cc",
     "public/util/dom_tree_extractor_browsertest.cc",
     "public/util/flat_dom_tree_extractor_browsertest.cc",
@@ -553,6 +556,7 @@ test("headless_browsertests") {
     "//base",
     "//components/crash/content/browser",
     "//components/security_state/content",
+    "//content/test:browsertest_support",
     "//content/test:test_support",
     "//testing/gmock",
     "//testing/gtest",