Merge Widevine CDM-Side Core Changes

This is a combined merge of several small changes to the core in the
Widevine CDM repository:

http://go/wvgerrit/10941
  Rename privacy_crypto to allow more variants.

http://go/wvgerrit/11530
  Add Missing Header to properties.h

http://go/wvgerrit/11531
  More Loosely Couple CdmEngine and CdmSession

Change-Id: I5b3f738ae495ab267da1440421dd7aa6f7860194

libwvdrmengine/cdm/core/include/properties.h

@@ -11,6 +11,10 @@
 #include "scoped_ptr.h"
 #include "wv_cdm_types.h"
 
+#if defined(UNIT_TEST)
+# include "gtest/gtest_prod.h"
+#endif
+
 namespace wvcdm {
 
 typedef std::map<CdmSessionId, const CdmClientPropertySet*>