[ios] Adds launchscreen image assets for Chromium.

ios/chrome/app/resources/BUILD.gn

 # Copyright 2016 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/config/locales.gni")
 import("//tools/grit/grit_rule.gni")
 import("//ios/chrome/app/resources/ios_chrome_repack.gni")
 
 grit("resources") {
   source = "ios_resources.grd"
@@ skipping 40 matching lines @@
   deps = [
     ":resources",
     "//components/resources",
     "//ios/web:resources",
     "//net:net_resources",
     "//ui/resources",
   ]
   output = "$target_gen_dir/resources.pak"
   copy_data_to_bundle = true
 }
+
+bundle_data("launchscreen_assets") {
+  sources = [
+    "launchscreen_images.xcassets/Contents.json",
+    "launchscreen_images.xcassets/launchscreen_app_logo.imageset/Contents.json",
+    "launchscreen_images.xcassets/launchscreen_app_logo.imageset/launchscreen_app_logo.png",
+    "launchscreen_images.xcassets/launchscreen_brand_name.imageset/Contents.json",
+    "launchscreen_images.xcassets/launchscreen_brand_name.imageset/launchscreen_brand_name.png",
+  ]
+  outputs = [
+    "{{bundle_resources_dir}}/{{source_file_part}}",
+  ]
+}