Issue 6183 - Reduce "Receiving end does not exist" exceptions

Issue 6183 - Reduce "Receiving end does not exist" exceptions

[kzar, 2017-12-12 15:52:51]

Patch Set 1

I can't see any purpose for sending this message here, but perhaps I'm missing
something. What do you guys think?

[Wladimir Palant, 2017-12-14 11:23:53]

On 2017/12/12 15:52:51, kzar wrote:
> I can't see any purpose for sending this message here, but perhaps I'm missing
> something. What do you guys think?

I managed to trace this change back to
https://hg.adblockplus.org/adblockpluschrome/rev/c911f94f1b43 - yes, that was
added a while ago. I found one scenario however where this code still serves a
purpose. Firefox will sometimes cache pages that you navigated away from, see
https://developer.mozilla.org/en-US/Firefox/Releases/1.5/Using_Firefox_1.5_ca....
This means that going back to the page won't reload it, it will rather restore
the exact previous state. How you can reproduce this:

* Go to https://news.ycombinator.com/
* Go to https://www.google.com/
* Press Alt+Left to go back in history.
* Now click ABP icon and choose "Block element" - start element selection (won't
always work in Firefox it seems, you might need to reload the page).
* Press Alt+Right to go forward in history, then Alt+Left to go back again.

Without your change, element selection on https://news.ycombinator.com/ will be
stopped when you go back to the page. If you remove this code however, Adblock
Plus will still be in the element selection mode.

I couldn't see any such behavior in Chrome, I guess that Chrome will always
reload pages when going back in history.

[kzar, 2017-12-20 15:43:01]

Patch Set 2 : Send the message, but ignore failures

I've not been able to reproduce the behaviour you described, but I've come up
with a possible fix. Would you be able to test that the "block element" tool no
longer gets messed up when the user navigates forward / back in Firefox with
this latest patch set?

[Wladimir Palant, 2017-12-21 10:34:24]

LGTM