Canvas prompt is not showing up anymore in Tor Browser based in ESR52

Going to https://github.com gives regularly the canvas prompt asking users what to do with a website wanting to access the canvas.

This is not happening anymore with an ESR52 based Tor Browser. Other sites are probably affected as well.

The blocking note is still visible on the browser console, though.

added TorBrowserTeam201704R component::applications/tor browser ff52-esr owner::tbb-team priority::high resolution::fixed severity::normal status::closed tbb-7.0-must-alpha tbb-e10s type::defect labels

When I tested on OSX, disabling e10s mode made the prompt work again.

Trac:
Cc: N/A to brade, mcs

This is a regression. Unless we plan to disable e10s, we should try to fix this for the alpha.

Trac:
Keywords: N/A deleted, tbb-7.0-must-alpha added

Trac:
Priority: Medium to High

Adding e10s keyword to track multiprocess related bugs.

Trac:
Keywords: N/A deleted, tbb-e10s added

It took a lot longer than we expected to find a working solution, but here is a fix for review: https://gitweb.torproject.org/user/brade/tor-browser.git/commit/?h=bug21778-01&id=04b228b078c98cabedc0ccc179d627d693884a42

Trac:
Keywords: N/A deleted, TorBrowserTeam201704R added
Status: new to needs_review

Hrr, this annoying popup again! Leave it for dumb users on Low Security only!

Replying to mcs:

It took a lot longer than we expected to find a working solution, but here is a fix for review: https://gitweb.torproject.org/user/brade/tor-browser.git/commit/?h=bug21778-01&id=04b228b078c98cabedc0ccc179d627d693884a42

Nice work! Looks good to me.

Looks good to me, too. Just one nit:

+    try {
+      browser = aSubject.QueryInterface(Ci.nsIBrowser);
+   } catch (e) {}

(indentation).

Here is a revised patch: https://gitweb.torproject.org/user/brade/tor-browser.git/commit/?h=bug21778-02&id=eee986e3824e8e872dd3cb38c2f6bf2a16f86d7b (it includes a second indentation fix too).

Thanks. This is commit 1182bee9789a632f374f0a6d3ed90f21af1e37c5 on tor-browser-52.1.0esr-7.0-2 now.

Trac:
Resolution: N/A to fixed
Status: needs_review to closed

Can't you just leave people who use "High" security? This popup is very annoying.

Trac:
Status: closed to reopened
Resolution: fixed to N/A

Replying to cypherpunks:

Can't you just leave people who use "High" security? This popup is very annoying. There's a related bug on Mozilla's bug tracker about not showing this popup until there's some user input, please don't mess up other tickets.

Trac:
Status: reopened to closed
Resolution: N/A to fixed

closed

mentioned in issue #21876 (moved)

moved to tpo/applications/tor-browser#21778 (closed)