Add precompiled headers to GN build for large targets.

ppapi/shared_impl/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.
 
 component("shared_impl") {
   output_name = "ppapi_shared"
 
   sources = [
     "array_var.cc",
     "array_var.h",
@@ skipping 133 matching lines @@
   if (is_win && current_cpu == "x64" && current_toolchain != default_toolchain) {
     sources -= [
       "ppb_audio_shared.cc",
       "ppb_graphics_3d_shared.cc",
       "ppb_opengles2_shared.cc",
       "private/net_address_private_impl.cc",
       "private/ppb_host_resolver_shared.cc",
     ]
   }
 
+  configs += [ "//build/config:precompiled_headers" ]
   defines = [
     "PPAPI_SHARED_IMPLEMENTATION",
 
     # This target goes in the same library as thunk (in GYP they are the same).
     "PPAPI_THUNK_IMPLEMENTATION",
   ]
 
   deps = [
     "//base",
     "//base:i18n",
@@ skipping 36 matching lines @@
   deps = [
     "//base/test:test_support",
     "//ipc",
     "//ipc:test_support",
     "//ppapi/proxy",
     "//ppapi/shared_impl",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }