1405001 - Error processing PAPZCTreeManager::Msg_SetTargetAPZC message when opening dropdown in remote webextension's options panel

Status: NEW

(Core :: Panning and Zooming, defect, P3)

Description

[Kartikaya Gupta (email:[e-mail])]

I found this while reviewing the patch for bug 1390445.

STR (mostly same as bug 1390445):
- Install the "Language Tool Grammar Checker 1.0.13" add-on (or one of other ones listed in that bug, but I only checked this one).
- Ensure that OOP webextensions are enabled (should be the default on Windows)
- Run the build so as to get console output (since this is Windows, need to use git bash or cygwin shell)
- Go to about:addons, go to the options for the addon, scroll down to the dropdowns, and click on a dropdown.

Actual:
- Console reports an error about the PAPZCTreeManager::Msg_SetTargetAPZC message. The message was deserialized, but the handler returned false (indicating failure).

Expected:
- No error

I verified that the layers id mismatch guard is getting hit at [1] although I'm not really sure why. This doesn't appear to have a user-facing effect, t least not that I can see.

[1] http://searchfox.org/mozilla-central/rev/298033405057ca7aa5099153797467eceeaa08b5/gfx/layers/ipc/APZCTreeManagerParent.cpp#214