Backward compatibility for licenses and certificates

Certificates and offline licenses are stored in security level
specific directories in klp. When devices transition from jb-mr2,
their persistent information has to be ported to these directories.

bug:10366036

Merge of https://widevine-internal-review.googlesource.com/#/c/7310/
from the widevine CDM repo

Change-Id: I70b4a79dc5b69bda7fc3a4b92fdcde7ef8b41836

libwvdrmengine/cdm/core/include/device_files.h

@@ -59,6 +59,8 @@ class DeviceFiles {
   bool RetrieveFile(const char* name, std::string* data);
 
  private:
+  virtual void SecurityLevelPathBackwardCompatibility();
+
   File* file_;
   CdmSecurityLevel security_level_;
   bool initialized_;