Add --headless flag to 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 318 matching lines @@
       "//chrome/app:command_ids",
       "//chrome/app/theme:chrome_unscaled_resources",
       "//chrome/common:features",
       "//chrome/install_static:install_static_util",
       "//chrome/install_static:secondary_module",
       "//chrome_elf",
       "//components/crash/content/app",
       "//components/policy:generated",
       "//content/app/resources",
       "//crypto",
+      "//headless:headless_shell_main_lib",
       "//net:net_resources",
       "//ppapi/features",
       "//third_party/cld",
       "//third_party/wtl",
       "//ui/views",
     ]
 
     ldflags = [
       "/DELAYLOAD:comdlg32.dll",
       "/DELAYLOAD:crypt32.dll",
       "/DELAYLOAD:cryptui.dll",
       "/DELAYLOAD:dhcpcsvc.dll",
       "/DELAYLOAD:dwmapi.dll",
       "/DELAYLOAD:imagehlp.dll",
       "/DELAYLOAD:imm32.dll",
       "/DELAYLOAD:iphlpapi.dll",
       "/DELAYLOAD:setupapi.dll",
       "/DELAYLOAD:urlmon.dll",
       "/DELAYLOAD:winhttp.dll",
       "/DELAYLOAD:wininet.dll",
       "/DELAYLOAD:winspool.drv",
       "/DELAYLOAD:ws2_32.dll",
       "/DELAYLOAD:wsock32.dll",
     ]
 
+    configs += [ "//headless:headless_implementation" ]

[Sami, 2017/03/20 11:53:10]

This doesn't seem right: the implementation build should only be enabled when
building the headless library itself.

Are you getting some linker errors without this? Perhaps there's an export macro
missing for some function/symbol?

[dvallet, 2017/03/22 07:14:17]

Fixed, the reason is that ChromeMain calls HeadlesShellMain which uses
HEADLESS_EXPORT and this required exporting this in this library. But I don't
really think that we need to add the export to the main method and so the config
is not needed. 

+
     if (!is_component_build) {
       # This is a large module that can't do incremental linking in some
       # cases.
       configs -= [ "//build/config/win:default_incremental_linking" ]
       configs +=
           [ "//build/config/win:default_large_module_incremental_linking" ]
     }
 
     if (use_aura) {
       deps += [ "//ui/compositor" ]
@@ skipping 46 matching lines @@
         ":chrome_dll_version",
         "//build/config/sanitizers:deps",
         "//chrome/browser/policy:path_parser",
         "//chrome/common:features",
         "//chrome/install_static:install_static_util",
         "//chrome/install_static:secondary_module",
         "//chrome_elf",
         "//components/browser_watcher:browser_watcher_client",
         "//components/crash/content/app",
         "//content/public/app:child",
+        "//headless:headless_shell_child_lib",
         "//pdf",
       ]
 
       ldflags = [
         "/DELAYLOAD:d3d11.dll",
         "/DELAYLOAD:d3d9.dll",
         "/DELAYLOAD:dwmapi.dll",
         "/DELAYLOAD:dxva2.dll",
         "/DELAYLOAD:esent.dll",
         "/DELAYLOAD:wininet.dll",
@@ skipping 1240 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}}",
     ]
   }
 }