[ Merge from go/wvgerrit/22920 ]
Automated tests reveal a race condition between closing
a session and the periodic policy timer event. If a close
session was in progress (WVDrmPlugin::closeSession) and
CdmEngine::CloseSession caused the CdmEngine::session_list_lock_
to be held, a call into CdmEngine::OnTimerEvent would pend on the
release of the lock.
The close session would continue to deallocate the session
and disable (stop) the policy timer leaving the CdmEngine::OnTimerEvent
call in an undefined state. This would result in an ANR.
This subtle race-condition was introduced when changes were made
to add in per-origin storage [ http://go/wvgerrit/17971 ]. This seems
to happen at a low frequency (~ < 0.5%).
To address a lock has been introduced to protect the map
WvContentDecryptionModule::cdms_.
Test: Unit tests + 200 aupt test iterations
b/33343891
Change-Id: I9788db8a7d1df84f0df82cdbadb9d0f0fbe21e4e
182f3c8058