disable C4125 on windows

third_party/protobuf/proto_library.gni

 # 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.
 
 # Compile a protocol buffer.
 #
 # Protobuf parameters:
 #
 #   proto_in_dir (optional)
 #       Specifies the path relative to the current BUILD.gn file where
@@ skipping 267 matching lines @@
       if (defined(invoker.generator_plugin_options)) {
         args += [
           "--plugin-options",
           invoker.generator_plugin_options,
         ]
       }
     }
 
     if (defined(invoker.import_dirs)) {
       foreach(path, invoker.import_dirs) {
-        args += ["--import-dir=" + rebase_path(path, root_build_dir)]
+        args += [ "--import-dir=" + rebase_path(path, root_build_dir) ]
       }
     }
 
     # System protoc is not used so it's necessary to build a chromium one.
     inputs = [
       protoc_path,
     ]
     deps = [
       protoc_label,
     ]
@@ skipping 67 matching lines @@
         if (defined(invoker.use_protobuf_full) &&
             invoker.use_protobuf_full == true) {
           public_deps = [
             "//third_party/protobuf:protobuf_full",
           ]
         } else {
           public_deps = [
             "//third_party/protobuf:protobuf_lite",
           ]
         }
+
+        if (is_win) {
+          cflags = [
+            # disable: C4125 decimal digit terminates octal escape sequence

[Peter Kasting, 2017/03/15 20:23:37]

Nit: I suggest adding:

protoc generates such sequences frequently, there's not an obviously superior
replacement behavior, and since this code is autogenerated, the warning will
never catch a legitimate bug.

[aizatsky, 2017/03/15 20:32:29]

done.

+            "/wd4125",
+          ]
+        }
       }
     }
 
     deps = [
       ":$action_name",
     ]
 
     # This will link any libraries in the deps (the use of invoker.deps in the
     # action won't link it).
     if (defined(invoker.deps)) {
       deps += invoker.deps
     }
   }
 }