Move `gn check` into the `generate_build_files` step.

components/html_viewer/BUILD.gn

 # Copyright 2014 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/module_args/v8.gni")
 import("//mojo/public/mojo_application.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
 import("//tools/grit/repack.gni")
 
@@ skipping 172 matching lines @@
     "//ui/events:gesture_detection",
     "//ui/events/blink",
     "//ui/events/gestures/blink",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/mojo/geometry:interfaces_cpp_sources",
     "//ui/mojo/ime:interfaces_cpp_sources",
     "//ui/mojo/init",
     "//ui/native_theme",
     "//url",
+    "//v8",
   ]
 
   public_deps = [
     "//components/mus/public/cpp",
     "//third_party/WebKit/public:blink",
     "//third_party/mojo/src/mojo/public/cpp/bindings",
   ]
 
   if (is_win) {
     sources += [ "html_viewer_version.rc" ]
@@ skipping 11 matching lines @@
   ]
 }
 
 mojo_native_application("html_viewer") {
   sources = [
     "html_viewer_main.cc",
   ]
   deps = [
     ":lib",
     ":pak",
+    "//base",
     "//mojo/application/public/cpp:sources",
     "//third_party/mojo/src/mojo/public/c/system:for_shared_library",
   ]
   resources = [ "$root_out_dir/html_viewer.pak" ]
 
   if (v8_use_external_startup_data) {
     resources += [
       "$root_build_dir/natives_blob.bin",
       "$root_build_dir/snapshot_blob.bin",
     ]
@@ skipping 115 matching lines @@
 
   data_deps = [
     ":html_viewer",
     "//components/mus",
   ]
 
   if (is_linux && !is_android) {
     data_deps += [ "//components/font_service" ]
   }
 }