375918 - docShell.contentViewer initially undefined in new blank tab

Status: NEW

(Core :: Layout, defect)

Description

[Myk Melez [:myk] [@mykmelez]]

I have an extension that accesses docShell.contentViewer in an onLocationChange handler.  Normally this works fine, but occasionally a window gets into a state where docShell.contentViewer is undefined for a new blank tab.

It doesn't stay undefined: if I break before my onLocationChange handler executes and then continue a moment later, then contentViewer is defined by the time my onLocationChange handler executes.  And contentViewer is immediately defined if I open a new non-blank tab (i.e. by opening a link/bookmark in a new tab).

Only new blank tabs exhibit this behavior.  And they only exhibit the behavior in that one window.  Other open windows (and newly opened windows) continue to work as expected.  But, once it breaks, that window remains broken for its lifetime.

During heavy browser use, I can reproduce this approximately once every couple of days.  I haven't yet found any pattern to the breakage.  I haven't yet tested on the trunk, so I don't know if this problem exists there.