Now that the new section "Third-Party Modules" in about:support (bug 1669036) has landed on the release version, let's start prototyping a new about:third-party page.

This patch adds a blank page about:third-party along with a skeleton XPCOM
object AboutThirdParty which has a method to invoke a background task in C++.

Depends on D109302

This patch implements a frontend part of the about:third-party, showing
third-party module info based on the telemetry ping as we currently do in
the "Third-Party Modules" section in the about:support page (bug 1669036).

Depends on D109303

This patch adds a feature to mark each module in the about:third-party page
as a shell extension or an IME if it is so. To achieve this, when the page
is loaded, it starts a background task to collect registered shell extensions
from the registry and adds a tag next to a module's name.

Depends on D109304

This patch adds application info (Name and Publisher for now) in the
about:third-party page if a module is a part of an installed application,
which is registered in the registry and shown in Windows Control Panel.
To achieve this, we parse the registry to collect installed applications
in the background task.

Depends on D109305

This patch adds a new mochitest to verify the content on about:third-party.
As a third-party module to test, this patch adds a new DLL TestShellEx.dll
which works as an Icon Handler Shell Extension.

Depends on D109306

This patch is to show a warning icon for a module which caused crash
i.e. if CrashManager has a record where the crashing address was within
the module's mapped region.

Backed out for causing failures at browser_all_files_referenced.js.

Backout link: https://hg.mozilla.org/integration/autoland/rev/f30905564afba06ec53064c9ef2ea8a63bb9bfe0

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&searchStr=linux%2C18.04%2Cx64%2Copt%2Cmochitests%2Ctest-linux1804-64%2Fopt-mochitest-browser-chrome-e10s%2Cbc1&revision=df4086427aaf2b2c327282538c73be915071a8ca&selectedTaskRun=Ydf3v30xRcqhly88wq-lKQ.0

Failure log: https://treeherder.mozilla.org/logviewer?job_id=341019385&repo=autoland&lineNumber=2618

Updated the part2 patch.

Backed out for causing build bustages.

Backout link: https://hg.mozilla.org/integration/autoland/rev/f6190339babcefdded79a0b47ea4dd035d777e06

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&revision=49be1caf65012a8f4f695f0e82786a097447a4c5&searchStr=Windows%2C2012%2Copt%2Cbuild-win32%2Fopt%2CB&selectedTaskRun=bXdxL1BaTiWgbAq5uFo86A.0

Failure log: https://treeherder.mozilla.org/logviewer?job_id=341036028&repo=autoland&lineNumber=36665

Hmm, somehow the icon file in the Part7 became empty.

Backed out 9 changesets (Bug 1695817) for causing bc failures in content/aboutThirdParty.js
Backout link: https://hg.mozilla.org/integration/autoland/rev/c884d008db5c45825972f442c7a8010eafd339fc
Push with failures, failure log

It seems MOZ_CRASHREPORTER is not defined in ASan build on autoland. Updated the Part8 patch.

https://hg.mozilla.org/mozilla-central/rev/9d48d8ab9d65
https://hg.mozilla.org/mozilla-central/rev/1bc11fed0fa7
https://hg.mozilla.org/mozilla-central/rev/01e6b8919218
https://hg.mozilla.org/mozilla-central/rev/cef7309a8e3c
https://hg.mozilla.org/mozilla-central/rev/9494a0c6f129
https://hg.mozilla.org/mozilla-central/rev/2e4e5decb750
https://hg.mozilla.org/mozilla-central/rev/a6a7d4df5ca4
https://hg.mozilla.org/mozilla-central/rev/3214e7781afd
https://hg.mozilla.org/mozilla-central/rev/df2befd2754e

Is this worth calling out in firefox 90 release notes, or not quite yet? (If yes, see https://wiki.mozilla.org/Release_Management/Release_Notes#Nomination_in_Bugzilla)

(In reply to Julien Cristau [:jcristau] from comment #23)

Is this worth calling out in firefox 90 release notes, or not quite yet? (If yes, see https://wiki.mozilla.org/Release_Management/Release_Notes#Nomination_in_Bugzilla)

Thank you for the suggestion. Yes, we want to add a note about this!

Release Note Request (optional, but appreciated)
[Why is this notable]: We introduce a new page for Windows users to see the list of third-party modules injected into Firefox. If they know this feature, they may be able to triage compatibility issues by themselves.
[Affects Firefox for Android]: No
[Suggested wording]: Firefox for Windows now offers a new page about:third-party to help users identify compatibility issues caused by third-party applications.
[Links (documentation, blog post, etc)]: We're preparing a SUMO article to which we want to have a link, but it's not available yet.

Can you help me understand where these two strings are used? I've been staring at the code for a while, and can't tell
https://hg.mozilla.org/mozilla-central/rev/01e6b8919218#l4.16

+third-party-header-module-list = Module list
+third-party-header-loading-events = Loading events

In the last is unclear if loading is a verb or an adjective. I assume it's a verb, which makes it sound like the string is missing an ellipsis at the end.

(In reply to Francesco Lodolo [:flod] from comment #25)

Can you help me understand where these two strings are used? I've been staring at the code for a while, and can't tell
https://hg.mozilla.org/mozilla-central/rev/01e6b8919218#l4.16

+third-party-header-module-list = Module list
+third-party-header-loading-events = Loading events

In the last is unclear if loading is a verb or an adjective. I assume it's a verb, which makes it sound like the string is missing an ellipsis at the end.

Oh, thank you for looking at the code. These are unused and I forgot to remove them. I'll file a bug.