Bug 20497: Check if the browser should run in portable mode at runtime (Base Browser)

Merge Info

Related Issues

• #20497 (closed)

Backport Timeline

• Immediate - patchsets for critical bug fixes or other major blocker (e.g. fixes for a 0-day exploit) OR patchsets with trivial changes which do not need testing (e.g. fixes for typos or fixes easily verified in a local developer build)
• Next Minor Stable Release - patchset that needs to be verified in nightly before backport
• Eventually - patchset that needs to be verified in alpha before backport
• No Backport - patchset for the next major stable

Upstream Merging

• Merge to base-browser - typically for !fixups to patches in the base-browser branch, though sometimes new patches as well
  • NOTE: if your changeset includes patches to both base-browser and tor-browser please please make separate merge requests for each part
  • This is Base Browser's part! See below.

Issue Tracking

• Link resolved issues with appropriate Release Prep issue for changelog generation
  • It depends if we're ending up closing the issue after this.

Change Description

This is almost the final objective for the portable mode: compile once and be able to run both portable and system-install.

I'm not sure the patch is upliftable, yet, but we could try at least to share our thoughts on Bug 1752975.

Also, I'm starting with Base Browser, because moving Tor Browser to a system install will also need changes to Tor Launcher. In general, I want to get rid of the --enable-tor-browser-data-outside-app-dir flag.

So, what I suggest for this patch is that we first review this part.

Then, once it's okay, I open another MR for Tor Browser, and finally we land them together.