[Webkit-unassigned] [Bug 187843] -[WKContentView(WKInteraction) _restoreFocusWithToken:] crashed

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=187843

--- Comment #10 from 894110476 at qq.com ---
Dear Wenson Hsieh:

We are sorry about that this is not a problem about webkit, we found a memory leak which is used to mananger navigationBar to webview controller. The problem was fixed after the memory leak was resolved. Thank you very much.  

(In reply to Wenson Hsieh from comment #7)
> Thanks for the information! From a quick glance, what could be happening is
> that we're getting an extra call to -_restoreFocusWithToken: when we don't
> expect to. The API (SPI?) contract for focus restoration is that each call
> to -_preserveFocusWithToken: should be bookended with exactly one call to
> -_restoreFocusWithToken:, so any mismatch here would cause us to crash in
> the UI process when we try and remove from _focusStateStack in this if
> statement:
> 
>     if (_focusStateStack.takeLast())
> 
> It probably makes sense to fail gracefully by bailing early if the focus
> state stack is empty here instead of merely debug asserting like we do now.
> That being said, the root cause is most likely beneath WebKit, in logic
> that's responsible for telling us to preserve or restore focus.
> 
> Regarding your comment in the other bug (181510):
> 
> > if we remove a webview when it is not on the top of navigationcontroller's viewcontrollers. when back to the 'webviewpage(had removed)', a crash will happen low frequently
> 
> Do you happen to have a test app that exercises this scenario? That would be
> very helpful in confirming a fix!

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