headless: Librarify Headless Shell

headless/BUILD.gn

 # Copyright 2015 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("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
 import("//tools/grit/repack.gni")
 
 config("headless_implementation") {
@@ skipping 328 matching lines @@
     ":embedder_mojo_for_testing",
     ":headless_browser_tests_pak",
     "//base",
     "//content/test:test_support",
     "//headless:headless_lib",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }
 
-executable("headless_shell") {
+static_library("headless_shell_lib") {
   sources = [
     "app/headless_shell.cc",
     "app/headless_shell_switches.cc",
     "app/headless_shell_switches.h",
+    "public/headless_shell.h",
   ]
 
   deps = [
     "//headless:headless_lib",
   ]
 }
+
+executable("headless_shell") {
+  sources = [
+    "app/headless_shell_main.cc",
+  ]
+
+  deps = [
+    "//headless:headless_shell_lib",
+  ]
+}