message: Clear up GenericStorageEntry
diff: @@ -299,24 +299,6 @@ message KeyEvent {
  optional int64 timestamp_msec = 10;
  }
  -message GenericStorageEntry {
  - enum StorageType {
  - SYMBOL_HISTORY = 0;
  - EMOTICON_HISTORY = 1;
  - EMOJI_HISTORY = 2;
  - }
  - optional StorageType type = 1;
  - optional string key = 2;
  - // The type must be bytes instead of string
  - // because value might have U+0000 character as a terminator.
  - // In this case, characters after the terminator are undefined.
  - // Such byte stream cannot be treaed by Java's String class, which
  - // is used for PB's string type.
  - // Instead, PB's bytes type is converted into ByteString in Java,
  - // which can treat C language style string described above.
  - repeated bytes value = 3;
  -}
  -
  message SessionCommand {
  enum CommandType {
  // Do nothing.
  @@ -1046,10 +1028,7 @@ message Input {
  // Client request
  optional Request request = 9;
  - // If the command is INSERT_TO_STORAGE, all the fields must be filled.
  - // If READ_ALL_FROM_STORAGE, key and value fields are ignored.
  - optional GenericStorageEntry storage_entry = 10;
  -
  + reserved 10; // Deprecated storage_entry
  reserved 11; // Deprecated auth_code
  enum TouchAction {
  @@ -1271,9 +1250,7 @@ message Output {
  }
  optional Callback callback = 18;
  - // Used when the command is READ_ALL_FROM_STORAGE.
  - optional GenericStorageEntry storage_entry = 19;
  -
  + reserved 19; // Deprecated storage_entry
  reserved 20; // Deprecated cloud_sync_status
  optional mozc.user_dictionary.UserDictionaryCommandStatus
  