Add runtime dependency extraction for GN.

tools/gn/BUILD.gn

 # Copyright (c) 2013 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("//testing/test.gni")
 
 defines = [ "GN_BUILD" ]
 
 static_library("gn_lib") {
   sources = [
@@ skipping 108 matching lines @@
     "output_file.cc",
     "output_file.h",
     "parse_tree.cc",
     "parse_tree.h",
     "parser.cc",
     "parser.h",
     "path_output.cc",
     "path_output.h",
     "pattern.cc",
     "pattern.h",
+    "runtime_deps.cc",
+    "runtime_deps.h",
     "scheduler.cc",
     "scheduler.h",
     "scope.cc",
     "scope.h",
     "scope_per_file_provider.cc",
     "scope_per_file_provider.h",
     "settings.cc",
     "settings.h",
     "setup.cc",
     "setup.h",
@@ skipping 112 matching lines @@
     "ninja_binary_target_writer_unittest.cc",
     "ninja_copy_target_writer_unittest.cc",
     "ninja_group_target_writer_unittest.cc",
     "ninja_target_writer_unittest.cc",
     "ninja_toolchain_writer_unittest.cc",
     "operators_unittest.cc",
     "parse_tree_unittest.cc",
     "parser_unittest.cc",
     "path_output_unittest.cc",
     "pattern_unittest.cc",
+    "runtime_deps_unittest.cc",
     "scope_per_file_provider_unittest.cc",
     "scope_unittest.cc",
     "source_dir_unittest.cc",
     "string_utils_unittest.cc",
     "substitution_pattern_unittest.cc",
     "substitution_writer_unittest.cc",
     "target_generator_unittest.cc",
     "target_unittest.cc",
     "template_unittest.cc",
     "test_with_scope.cc",
@@ skipping 12 matching lines @@
 }
 
 executable("generate_test_gn_data") {
   sources = [
     "generate_test_gn_data.cc",
   ]
   deps = [
     "//base",
   ]
 }