process, we need to open a connection to it. If we create a list of targets without care, we could suffer a performance hit, since every target requires that we spin up a server in its dedicated process, along with a loader, and all of its associated actors -- when all we want is potentially the URL -- or to just know that it exists. Spinning up all targets at once is almost never necessary, usually we want a list of metadata from the targets so we can iterate over them (for example the about:debugging panel does this). We need an api that allows us to work with listing and selecting targets safely.

This is a first pass at this idea, which will implement a metaclass for processes, which is the only target type that is not represented by a proxy, but by a json object.

WIP for metaclass concept

The best place to start is the test, it outlines what the API looks like.

Backed out 2 changesets (bug 1566450) for causing browser_aboutdebugging_process_main_local.js to perma fail

push that caused the backout: https://treeherder.mozilla.org/#/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel%2Crunning%2Cpending%2Crunnable&searchStr=os%2Cx%2C10.14%2Cdebug%2Cmochitests%2Ctest-macosx1014-64%2Fdebug-mochitest-devtools-chrome-e10s-2%2Cm%28dt2%29&revision=b0eee59fb22c62f7afd987b65407506edb4b6f31

failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&selectedJob=258965375&fromchange=3133ef9a77a3f178d3a8b77dea0abb0b2e3d349f&searchStr=os%2Cx%2C10.14%2Cdebug%2Cmochitests%2Ctest-macosx1014-64%2Fdebug-mochitest-devtools-chrome-e10s-2%2Cm%28dt2%29

backout: https://hg.mozilla.org/integration/autoland/rev/a68fa605c6a45bcf94df9e00fdf8169304602c9f

I am looking into this but it is trickier than I thought. It looks to be due to the destruction order of targets, specifically -- the process target doesn't unmanage itself when destroyed. Not sure how that is happening.

Will keep looking

https://hg.mozilla.org/mozilla-central/rev/e603094e855a
https://hg.mozilla.org/mozilla-central/rev/4c1d22f89c09
https://hg.mozilla.org/mozilla-central/rev/8edf73d4926a