Add a GN flag for the Windows multi-dll build.

components/policy/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/config/chrome_build.gni")
 import("//build/config/features.gni")
-import("resources/policy_templates.gni")
+import("//components/policy/resources/policy_templates.gni")
 import("//third_party/protobuf/proto_library.gni")
 import("//tools/grit/grit_rule.gni")
 
 # About the policy component:
 #
 # There should really be two components. One called "policy" that includes all
 # generated code, and one "policy/proto" liek we have now. The proto needs to
 # be separate for cases like SesssionManagerClient which uses the protos to
 # communicate with the Chrome OS system layer, but doesn't need the rest of the
 # policy stuff).
@@ skipping 307 matching lines @@
 
       deps = [
         ":${target_name}__consolidate_resources",
         ":${target_name}__build_config",
         ":${target_name}__create_zip",
       ]
     }
   }
 }
 #TODO(GYP) chrome_manifest_bundle