GN: Specify grit generated output paths to be the same as gyp's.

chrome/common/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("//tools/grit/grit_rule.gni")
 
 gypi_values = exec_script(
     "//build/gypi_to_gn.py",
     [ rebase_path("../chrome_common.gypi") ],
     "scope",
     [ "../chrome_common.gypi" ])
 
 # GYP version: chrome/chrome_resources.gyp:chrome_resources
 #              (generate_common_resources action)
 grit("resources") {
   source = "common_resources.grd"
+  output_dir = "$root_gen_dir/chrome"
   outputs = [
     "grit/common_resources.h",
     "common_resources.pak",
   ]
 }
 
 # GYP version: chrome/chrome_resources.gyp:chrome_resources
 #              (generate_extensions_api_resources action)
 grit("extensions_api_resources") {
   source = "extensions_api_resources.grd"
+  output_dir = "$root_gen_dir/chrome"
   outputs = [
     "grit/extensions_api_resources.h",
     "extensions_api_resources.pak",
   ]
 }
 
 # GYP version: chrome/chrome_common.gyp:common
 static_library("common") {
   sources = rebase_path(gypi_values.chrome_common_sources, ".", "//chrome")
   defines = []
@@ skipping 263 matching lines @@
     "//components/bookmarks/common",
     "//third_party/widevine/cdm:version_h",
   ]
 
   if (enable_nacl) {
     deps += [
       #'../components/nacl.gyp:nacl_switches',  TODO(GYP)
     ]
   }
 }