In https://phabricator.services.mozilla.com/D118569#4015156, @robwu wrote:

Do not export ExtensionManager. Could you create a new patch or bug to take care of removing it? It's not as trivial as exporting it, and I'd like to have a minimal patch for such a refactor.

ExtensionManager is used in two tests:

• https://searchfox.org/mozilla-central/source/toolkit/components/extensions/test/mochitest/test_ext_contentscript_cache.html
• https://searchfox.org/mozilla-central/source/toolkit/components/extensions/test/xpcshell/test_ext_schemas_interactive.js

Its use is basically ExtensionManager.extensions.get(extensionId);
That can be replaced with a call to ExtensionProcessScript.getExtensionChild(extensionId);

Changing severity to N/A because this is a task.

There's a r+ patch which didn't land and no activity in this bug for 2 weeks.
:mathew.hodson, could you have a look please?
For more information, please visit auto_nag documentation.

The patch stack appears to be blocked on review from someone else.

To avoid bitrot, I suggest to split off the SubprocessImpl changes to a separate patch and land everything at once @mathew, as suggested at https://phabricator.services.mozilla.com/D118569#4155831

I don't have access to land patches. Can you land the first four patches in the stack?

I will work on splitting up the last patch that hasn't been approved.

I've pushed to land.

https://hg.mozilla.org/mozilla-central/rev/294465905b58