disable C4125 on windows

third_party/protobuf/proto_library.gni

Index: third_party/protobuf/proto_library.gni
diff --git a/third_party/protobuf/proto_library.gni b/third_party/protobuf/proto_library.gni
index 84373f39d08278ba0bf11a483ed8810806377ed7..880a5af48dc927bc260e939fe96a2e4dd8f3479c 100644
--- a/third_party/protobuf/proto_library.gni
+++ b/third_party/protobuf/proto_library.gni
@@ -285,7 +285,7 @@ template("proto_library") {
 
     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) ]
       }
     }
 
@@ -373,6 +373,16 @@ template("proto_library") {
             "//third_party/protobuf:protobuf_lite",
           ]
         }
+
+        if (is_win) {
+          cflags = [
+            # disable: C4125 decimal digit terminates octal escape sequence
+            # Protoc generates such sequences frequently, there's no obvious
+            # superior replacement behavior. Since this code is autogenerated,
+            # the warning would never catch a legitimate bug.
+            "/wd4125",
+          ]
+        }
       }
     }