handleG3_(controlCode) {
    if (!this.currentWindow_) {
      return;
    }

    // As of CEA-708-E, the G3 group only contains 1 character. It's a
    // [CC] character which has no unicode value on 0xa0.
    if (controlCode != 0xa0) {
      // Similar to G2, the spec decrees an underline if char is unsupported.
      this.currentWindow_.setCharacter('_');
      return;
    }

    this.currentWindow_.setCharacter('[CC]');
  }
Handles G3 group data.
@param {number} controlCode
@private