[headless] Fix screenshots with gpu enabled.

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("//build/config/chrome_build.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
 import("//tools/grit/repack.gni")
 
@@ skipping 318 matching lines @@
     "test/test_url_request_job.cc",
     "test/test_url_request_job.h",
   ]
 
   data = [
     "$root_out_dir/headless_browser_tests.pak",
     "$root_out_dir/headless_lib.pak",
     "//net/tools/testserver/",
     "//third_party/pyftpdlib/",
     "//third_party/pywebsocket/",
+    "//third_party/skia/",
     "//third_party/tlslite/",
     "test/data/",
   ]
 
   defines = [ "HAS_OUT_OF_PROC_TEST_RUNNER" ]
 
   deps = [
     ":embedder_mojo_for_testing",
     ":headless_browser_tests_pak",
     "//base",
@@ skipping 19 matching lines @@
 
 executable("headless_shell") {
   sources = [
     "app/headless_shell_main.cc",
   ]
 
   deps = [
     "//headless:headless_shell_lib",
   ]
 }