Add support for Edge extensions to buildtools

[kvas]

Background

We're rolling out a version of Adblock Plus for Edge and in order to reduce the amount of manual work and maintain consistency of the process we need to add the functionality of building its package (.appx) to the toolkit that is currently used for building other extensions (buildtools).

Disclaimer: this is based on available information and example package and is not complete. Any corrections or additions are welcome.

Edge package has the content of a Chrome package with minor modifications, arranged slightly differently, supplemented with additional metadata and packaged in a specifically laid out zip archive:

• The main extension files that are located at the root of the zip archive in a Chrome extension are placed in Extension folder in an Edge extension,
• Additional icons are placed in Assets folder,
• The root folder of an Edge extension also contains three additional files:
  • AppxManifest.xml -- metadata of the package for extension store,
  • AppxBlockMap.xml -- block map that contains sha256 checksums of packed files and information about zip file layout,
  • [Content_Types].xml -- content types of the files in the extension.
• There are differences between Chrome manifest.json and Edge Extension/manifest.json:
  • The content of background key is different,
  • minimum_chrome_version key is replaced with minimum_edge_version.
• The files have to be placed into a zip archive in accordance with the block map (normally it means that the block map is generated when packing all the other files).

References

• Creating an Edge Extension Appx.pdf,
• ​App package block map,
• ​Open source cross-platform Appx packager written by Facebook,
• ​Zip file format specification.

What to change

• Add edge to the list of plugin types in ​build.py.
• Add packagerEdge.py that produces the package for Edge. Reuse existing generic and Chrome-specific functionality for producing the initial layout and manifest.js. Modify the manifest and rearrange the files to match Appx layout, generate additional Appx metadata files and produce the Appx file.

[abpbot]

A commit referencing this issue has landed:
​Fixes 4028 - Add support for Edge extensions to buildtools