The drm resource manager expects openSession to fail
with ERROR_DRM_RESOURCE_BUSY, but in some cases the
WV DRM plugin is returning a vendor-specific code
kErrorTooManySessions instead. This change updates
the error code mapping to match what the resource
manager expects.
Merge of http://go/wvgerrit/14564 from widevine repo
bug: 21640598
Change-Id: I0b296ff5eeef8a6b94cfe0fd450b15f15cf03eab