Support Device Unprovisioning

Merge of https://widevine-internal-review.googlesource.com/#/c/10845/
from the widevine cdm repo.

Bug: 12247651
Change-Id: Ice6ec95865640fa2f736c7a9f09956395d648337

libwvdrmengine/mediadrm/include/WVDrmPlugin.h

@@ -81,6 +81,8 @@ class WVDrmPlugin : public android::DrmPlugin,
                                             Vector<uint8_t>& certificate,
                                             Vector<uint8_t>& wrapped_key);
 
+  virtual status_t unprovisionDevice();
+
   virtual status_t getSecureStops(List<Vector<uint8_t> >& secureStops);
 
   virtual status_t releaseSecureStops(const Vector<uint8_t>& ssRelease);