Get headless_shell building on Windows.

chrome/BUILD.gn

 # Copyright 2014 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("//build/buildflag_header.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/compiler/pgo/pgo.gni")
 import("//build/config/features.gni")
 import("//build/config/locales.gni")
@@ skipping 174 matching lines @@
         "//chrome/install_static:secondary_module",
         "//chrome/installer/util:with_no_strings",
         "//chrome_elf",
         "//components/browser_watcher:browser_watcher_client",
         "//components/crash/content/app:run_as_crashpad_handler",
         "//components/flags_ui:switches",
         "//content:sandbox_helper_win",
         "//content/public/common:static_switches",
         "//crypto",
         "//sandbox",
+
+        # For headless mode.

[dvallet, 2017/03/01 02:40:39]

This is breaking the component_build, and it requires actually some work on
reorganizing headless libraries to make this work. 
I suggest that you revert this file and submit the CL as is and I'll work on how
to add the dependency for component builds.

+        "//headless:headless_shell_lib",
       ]
       data_deps = [
         "//chrome/app/version_assembly:version_assembly_manifest",
       ]
 
       if (win_console_app) {
         defines += [ "WIN_CONSOLE_APP" ]
       } else {
         # Set /SUBSYSTEM:WINDOWS for chrome.exe itself, unless a console build
         # has been requested.
@@ skipping 1452 matching lines @@
       "//chrome/app/theme/$branding_path_component/product_logo_48.png",
       "//chrome/tools/build/linux/chrome-wrapper",
       "//third_party/xdg-utils/scripts/xdg-mime",
       "//third_party/xdg-utils/scripts/xdg-settings",
     ]
     outputs = [
       "$root_out_dir/{{source_file_part}}",
     ]
   }
 }