errors.push({ warn });
    }

    if (purposes.size === 0) {
      const warn = domBundle.formatStringFromName("ManifestImageUnusable", [
        aMemberName,
        index,
      ]);
      errors.push({ warn });
      throw new TypeError(warn);
    }

    return [...purposes];
  }

  function processTypeMember(aImage) {
    const charset = {};
    const hadCharset = {};
    const spec = {
      objectName: "image",
      object: aImage,
      property: "type",
      expectedType: "string",
      trim: true,
    };
    let value = extractor.extractValue(spec);
    if (value) {
      value = Services.io.parseRequestContentType(value, charset, hadCharset);
    }
    return value || undefined;
  }

  function processSrcMember(aImage, aBaseURL, index) {
    const spec = {
      objectName: aMemberName,
      object: aImage,
      property: "src",
      expectedType: "string",
      trim: false,
      throwTypeError: true,
    };
    const value = extractor.extractValue(spec);
    let url;
    if (typeof value === "undefined" || value === "") {
      // We throw here as the value is unusable,
      // but it's not an developer error.
      throw new TypeError();
    }
    if (value && value.length) {
      try {
        url = new URL(value, aBaseURL).href;
      } catch (e) {
        const warn = domBundle.formatStringFromName(
          "ManifestImageURLIsInvalid",
          [aMemberName, index, "src", value]
        );
        errors.push({ warn });
        throw e;
      }
    }
    return url;
  }

  function processSizesMember(aImage) {
    const sizes = new Set();
    const spec = {
      objectName: "image",
      object: aImage,
      property: "sizes",
      expectedType: "string",
      trim: true,
    };
    const value = extractor.extractValue(spec);
    if (value) {
      // Split on whitespace and filter out invalid values.
      value
        .split(/\s+/)
        .filter(isValidSizeValue)
        .reduce((collector, size) => collector.add(size), sizes);
    }
    return sizes.size ? Array.from(sizes) : undefined;
    // Implementation of HTML's link@size attribute checker.
    function isValidSizeValue(aSize) {
      const size = aSize.toLowerCase();
      if (ImageObjectProcessor.anyRegEx.test(aSize)) {
        return true;
      }
      if (!size.includes("x") || size.indexOf("x") !== size.lastIndexOf("x")) {
        return false;
      }
      // Split left of x for width, after x for height.
      const widthAndHeight = size.split("x");
      const w = widthAndHeight.shift();
      const h = widthAndHeight.join("x");
      const validStarts = !w.startsWith("0") && !h.startsWith("0");
      const validDecimals = ImageObjectProcessor.decimals.test(w + h);
      return validStarts && validDecimals;
    }
  }
};
PK