Merge from Widevine repo of http://go/wvgerrit/135982
The basic test was failing when using the testbed oemcrypto
because the testbed deletes its keybox on each
initialization. The test would terminate and re-initialize
oemcrypto whenever all the crypto sessions are deleted. This
has been fixed by holding a crypto session alive until the
end of the test.
bug: 187646550
Test: test only code
Change-Id: I48a3771bf5fd4aae8d262b8c7bf42f004d9b9f4c
3eef7e60b3