libchromeos: Fix memory leak in chromeos::http::FormField

The base class chromeos::http::FormField was missing a virtual destructor
so the derived class destructors weren't called when the form fields were
deleted through a pointer to the base class.

BUG=chromium:481152,chromium:481872
TEST=`FEATURES=test USE="clang asan" emerge-link libchromeos`

Change-Id: I9cdc3dfbff76dc9eff3b1d508eab01f7f92ccecd
Reviewed-on: https://chromium-review.googlesource.com/269994
Trybot-Ready: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
1 file changed