add customized printing setting for headless

headless/BUILD.gn

Index: headless/BUILD.gn
diff --git a/headless/BUILD.gn b/headless/BUILD.gn
index 55afe1f2833a2df59119165ab9391dc0350a1be4..11dd554b25b19fcd4e044919dbd0f1419a65feab 100644
--- a/headless/BUILD.gn
+++ b/headless/BUILD.gn
@@ -25,10 +25,32 @@ group("headless") {
   ]
 }
 
+repack_locales("locale_pak") {

[Eric Seckler, 2017/04/20 09:15:28]

I'm not very familiar with locales. Can you explain why we need this extra pak
and can't just use the ui/strings paks we include in repack("pak") below? There,
we also include ui/strings/app_locale_settings_en-US.pak and
ui/strings/ui_strings_en-US.pak.

[jzfeng, 2017/04/27 06:56:05]

The locale pak is loaded by ResourceBundle::LoadLocaleResources in
resource_bundle.cc.
On Linux, the fallback app_locale is "en-US", and it tries to find the en-US.pak
file.
On Mac, it tries to find locale.pak file.
Chrome generates this file, while headless shell doesn't. That's why we see 
"locale_file_path.empty() for locale"
warning when running headless shell.

If we want to reuse repack("pak") below, we need to change its output from
headless_lib.pak to en-US.pak or locale.pak depend on the platform. This option
doesn't looks so good to me.

[Eric Seckler, 2017/04/27 08:57:00]

I have two concerns about this:
a) Would this have a significant binary size impact?
b) Would this create problems for building with embedded resources
(headless_use_embedded_resources)? Can we do the same for these locale paks as
we do for headless_lib.pak, or is that difficult because of the way the ui/ code
loads these locale paks?

+skyostil for a)
+altimin for b)

[altimin, 2017/04/27 15:16:34]

Yes, current approach does not support embedded resources. We should add the
option to provide locale resources as embedded content. Something along these
lines should work:
- InitSharedInstanceWithLocale should be able to skip loading resources (a new
setting in ResourceBundle::LoadResources?)
- Add an option to load locale resources directly from a DataPack (we already
can create a data pack from a buffer).
ResourceBundle::ReloadLocaleResoucesFromDataPack?

I'd recommend doing that in a separate CL and looping in sadrul@ and sky@ as
ui/base owners. If you have any questions, I'd be happy to answer.

[jzfeng, 2017/05/02 07:50:55]

Thanks for the help!
Managed to find a way to avoid using the locale pak for now.

+  input_locales = [ "en-US" ]
+
+  if (!is_mac) {
+    output_locales = [ "en-US" ]
+  } else {
+    output_locales = [ "locale" ]
+  }
+
+  source_patterns = [
+    "$root_gen_dir/ui/strings/app_locale_settings_",
+    "$root_gen_dir/ui/strings/ui_strings_",
+  ]
+
+  deps = [
+    "//ui/strings",
+  ]
+
+  output_dir = "$root_out_dir/headless_locales"
+}
+
 repack("pak") {
   sources = [
     "$root_gen_dir/blink/public/resources/blink_image_resources_100_percent.pak",
     "$root_gen_dir/blink/public/resources/blink_resources.pak",
+    "$root_gen_dir/components/components_resources.pak",
     "$root_gen_dir/components/strings/components_strings_en-US.pak",
     "$root_gen_dir/content/app/resources/content_resources_100_percent.pak",
     "$root_gen_dir/content/app/strings/content_strings_en-US.pak",
@@ -51,6 +73,7 @@ repack("pak") {
 
   deps = [
     ":resources",
+    "//components/resources:components_resources",
     "//components/strings",
     "//content:resources",
     "//content/app/resources",
@@ -323,6 +346,7 @@ static_library("headless_lib") {
 
   deps = [
     ":gen_devtools_client_api",
+    ":locale_pak",
     ":tab_socket",
     ":version_header",
     "//components/crash/content/browser",