shill: DHCPProviderTest.BindAndUnbind: Work around ASAN issue

Asan seems not to be able to use SaveArg with closures.  Work
around this by calling the task directly.

BUG=chromium:502319,chromium:502320
TEST=Run shill unittests with USE="asan clang"

Change-Id: Ib97e99ed6a6331ed43fbd04a359095b01de80f47
Reviewed-on: https://chromium-review.googlesource.com/280587
Reviewed-by: Samuel Tan <samueltan@chromium.org>
Tested-by: Samuel Tan <samueltan@chromium.org>
Commit-Queue: Paul Stewart <pstew@chromium.org>
1 file changed