unable to parse default ibus config
https://github.com/google/mozc/issues/685


Reproducible: Always

Steps to Reproduce:
1. set active_on_launch: True
2. `ibus write-cache; ibus restart`
Actual Results:  
[libprotobuf ERROR google/protobuf/text_format.cc:335] Error parsing text-format mozc.ibus.Config: 19:22: Expected integer or identifier, got: "HIRAGANA"
[libprotobuf ERROR google/protobuf/text_format.cc:335] Error parsing text-format mozc.ibus.Config: 19:22: Expected integer or identifier, got: "HIRAGANA"

Expected Results:  
fix it

my ibus_config.textproto

# `ibus write-cache; ibus restart` might be necessary to apply changes.
engines {
  name : "mozc-jp"
  longname : "Mozc"
  layout : "default"
  layout_variant : ""
  layout_option : ""
  rank : 80
  symbol : "あ"
}
engines {
  name : "mozc-on"
  longname : "Mozc:あ"
  layout : "default"
  layout_variant : ""
  layout_option : ""
  rank : 99
  symbol : "あ"
  composition_mode : "HIRAGANA"
}
engines {
  name : "mozc-off"
  longname : "Mozc:A_"
  layout : "default"
  layout_variant : ""
  layout_option : ""
  rank : 99
  symbol : "A"
  composition_mode : "DIRECT"
}
active_on_launch: True