Chromium crashes with SEGFAULT when the MHTML save dialog is closed

[TjWallas]

Description

When the MHTML archiving option is checked, on bookmarking a site and pressing save for the MHTML file save dialog, chromium version 70.0.3538.77 crashes with a segmentation fault.

How to reproduce

1. Go to the extension settings and enable the two MHTML archiving options
2. Go to some website which has not been bookmarked before
3. Press the chromium star-shaped bookmark button

Behavior

The MHTML file save dialog appears. But when you press save, chromium crashes.

More debugging info

OS

Ubuntu MATE 16.04 LTS, Linux kernel 4.4.0-138-generic

Chromium Version

Chromium	70.0.3538.77 (Official Build) Built on Ubuntu , running on Ubuntu 16.04 (64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Linux
JavaScript	V8 7.0.276.32
Flash	(Disabled)
User Agent	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/70.0.3538.77 Chrome/70.0.3538.77 Safari/537.36

Chromium debug lines from console

[8232:8232:1101/113207.149947:ERROR:input_method_base.cc(146)] Not implemented reached in virtual ui::InputMethodKeyboardController *ui::InputMethodBase::GetInputMethodKeyboardController()Usi
ng InputMethodKeyboardControllerStub
[8232:8232:1101/113230.937874:ERROR:textfield.cc(1767)] Not implemented reached in virtual bool views::Textfield::ShouldDoLearning()
Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.
[1]    8232 segmentation fault (core dumped)  chromium-browser

[rahiel]

Thanks for reporting.

I can reproduce this on Version 70.0.3538.110 (Developer Build) built on Debian buster/sid, running on Debian buster/sid (64-bit). In my build of Chromium the save file dialog does not appear when a bookmark is auto-archived as MHTML, it makes and saves the archive without trouble. It does crash when I click save or cancel when manually saving a page as MHTML.

[rahiel]

This is most probably a bug in GTK+ or in Chromium.

TODO: https://wiki.debian.org/Chromium/Debugging