Oilpan: insist on persisted plugin disposal upon clearing.
Follow up r355010 and arrange for persisted plugin widget disposal
when the plugin is completely detached and removed from the tree.
r355010 restricted disposal to not happen for persisted widgets
when re-attaching, but also ended up not disposing for the
fully-detached persistent plugin widget case.
Lacking those, widgets would end up being finalized without their
required dispose() having been called first.
R=haraken
BUG=544175
Review URL: https://codereview.chromium.org/1422503009
Cr-Commit-Position: refs/heads/master@{#357142}
1 file changed
