Add precompiled headers to GN build for large targets.

storage/browser/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.
 
 # GYP version: storage/storage_browser.gyp:storage
 component("browser") {
   output_name = "storage_browser"
   sources = [
     "blob/blob_data_builder.cc",
     "blob/blob_data_builder.h",
@@ skipping 153 matching lines @@
     "quota/storage_monitor.h",
     "quota/storage_observer.cc",
     "quota/storage_observer.h",
     "quota/usage_tracker.cc",
     "quota/usage_tracker.h",
     "storage_browser_export.h",
   ]
 
   defines = [ "STORAGE_BROWSER_IMPLEMENTATION" ]
   configs += [
+    "//build/config:precompiled_headers",
+
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
     "//build/config/compiler:wexit_time_destructors",
   ]
 
   deps = [
     "//base",
     "//base:i18n",
     "//base/third_party/dynamic_annotations",
     "//net",
@@ skipping 16 matching lines @@
   sources = [
     "fileapi/dump_file_system.cc",
   ]
 
   deps = [
     ":browser",
     "//base",
     "//storage/common",
   ]
 }