Since CryptoSession::RewrapDeviceRSAKey takes a const std::string& nonce, the calling code
implicitly constructa temporary std::string from a character array with undefined termination
and sometimes bogus value when nonce.data() is passed in.
Bug: 9016828
Merge of https://widevine-internal-review.googlesource.com/#/c/5690/
from the Widevine CDM repository
Change-Id: Ia3beaa5f1a96924a8cc53a719f25af52217b8cc5