Merge from widevine of http://go/wvgerrit/14263
The unit test PreventNonceFlood3 opens 8 sessions and floods the nonce
table. It then opens one more session after a pause to verify that it
can still request nonces. However, there is no requirement that we
can open more than 8 sessions. This CL reuses one of the already open
sessions to verify that we can continue generating nonces.
Change-Id: If35f146477bd21e381ec5375dde7ec7fdbe8f366
48e84580e9