Merge "Fix a log issue in ui.cpp."

  // we don't have a good way to query the default value.

  std::string content;

  if (!android::base::ReadFileToString(MAX_BRIGHTNESS_FILE, &content)) {

    LOG(WARNING) << "Failed to read max brightness: " << content;

    PLOG(WARNING) << "Failed to read max brightness";

    return false;

  }