Add local suppresion for -Wparentheses and enable everywhere on Windows.

cloud_print/service/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.
 
 import("//tools/grit/grit_rule.gni")
 
 source_set("cloud_print_service_lib") {
   sources = [
     "//cloud_print/common/win/cloud_print_utils.cc",
     "//cloud_print/common/win/cloud_print_utils.h",
@@ skipping 21 matching lines @@
     ":service_resources",
     "//base",
     "//base:base_static",
     "//base/third_party/dynamic_annotations",
     "//content/public/common",
     "//google_apis",
     "//ipc",
     "//net",
     "//url",
   ]
+
+  if (is_clang) {
+    cflags = [ "-Wno-parentheses" ]
+  }
 }
 
 grit("service_resources") {
   source = "win/service_resources.grd"
   outputs = [
     "resources.h",
     "service_resources_en.rc",
   ]
 }