(This is a merge of http://go/wvgerrit/72867)
This patch replaces the previous static std::mutexes in CryptoSession
with shared_mutexes, allowing multiple readers to access the resources
they protect. For the shared fields, this means only Initialize(),
Terminate(), and the code that sets up the usage table headers needs
exclusive access. All other CryptoSession code is able to read these
fields in parallel.
For OEMCrypto, the static OEMCrypto lock is joined by a per-session
std::mutex, which are used in concert to enforce the OEMCrypto v15
threading guarantees.
On my machine this results in a noticeable increase in performance for
the parallel unit tests.
Bug: 70889998
Bug: 118584039
Test: CE CDM Unit Tests
Test: Android Unit Tests
Test: Jenkins Tests
Change-Id: Ie6332ae4926ed4f14af897685d37bfe63831b14f
e10ac3b465