Reduce absolute paths in generated ninja files

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("//build/util/process_version.gni")
 import("//headless/headless.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//printing/features/features.gni")
 import("//testing/test.gni")
@@ skipping 66 matching lines @@
     "$root_out_dir/headless_lib.pak",
   ]
 
   outputs = [
     "$root_gen_dir/headless/embedded_resource_pak.cc",
     "$root_gen_dir/headless/embedded_resource_pak.h",
   ]
 
   args = [
     "--data_file",
-    rebase_path("$root_out_dir/headless_lib.pak"),
+    rebase_path("$root_out_dir/headless_lib.pak", root_build_dir),
     "--gendir",
-    rebase_path("$root_gen_dir"),
+    rebase_path("$root_gen_dir", root_build_dir),
     "--header_file",
     "headless/embedded_resource_pak.h",
     "--source_file",
     "headless/embedded_resource_pak.cc",
     "--namespace",
     "headless",
     "--variable_name",
     "kHeadlessResourcePak",
   ]
 
@@ skipping 12 matching lines @@
 }
 
 grit("resources") {
   source = "lib/resources/headless_lib_resources.grd"
   outputs = [
     "grit/headless_lib_resources.h",
     "$root_gen_dir/headless/headless_lib_resources.pak",
   ]
   grit_flags = [
     "-E",
-    "mojom_root=" + rebase_path(root_gen_dir),
+    "mojom_root=" + rebase_path(root_gen_dir, root_build_dir),
   ]
   deps = [
     ":tab_socket__generator",
   ]
 }
 
 devtools_domains = [
   "accessibility",
   "animation",
   "application_cache",
@@ skipping 56 matching lines @@
     "lib/browser/devtools_api/domain_type_conversions_h.template",
     "lib/browser/devtools_api/domain_types_cc.template",
     "lib/browser/devtools_api/domain_types_forward_declarations_h.template",
     "lib/browser/devtools_api/domain_types_h.template",
   ]
 
   args = [
     "--protocol",
     rebase_path(inputs[0], root_build_dir),
     "--output_dir",
-    rebase_path(target_gen_dir) + "/public",
+    rebase_path(target_gen_dir, root_build_dir) + "/public",
   ]
 }
 
 if (headless_fontconfig_utils) {
   static_library("headless_fontconfig_utils") {
     sources = [
       "public/util/fontconfig.cc",
       "public/util/fontconfig.h",
     ]
 
@@ skipping 492 matching lines @@
 
 executable("headless_example") {
   sources = [
     "app/headless_example.cc",
   ]
 
   deps = [
     ":headless_shell_lib",
   ]
 }