Expose status, add backward compat in tests and remove unused code

* Expose release and offline statuses in CdmEngine.

  [ Merge of http://go/wvgerrit/14616 ]

  This will allow me to make some intelligent decisions in the new CE
  CDM implementation without having to duplicate all the information
  known in the lower levels.

* Account for backward compat support in tests

  [ Merge of http://go/wvgerrit/14621 ]

  One test ensures that device path backward compatibility is working,
  while another assumes it is used.

  This fixes test results when
  Properties::security_level_path_backward_compatibility_support()
  is false.

  Previously, the CE CDM did not run these tests, and so this went
  unnoticed.

* Remove Lock::Try, which is not used.

  [ Merge of http://go/wvgerrit/14624 ]

Change-Id: Id18cf1f5b18c7322b8b636819276361af225734f

libwvdrmengine/cdm/core/include/cdm_engine.h

@@ -104,12 +104,14 @@ class CdmEngine {
   // Query session information
   virtual CdmResponseType QuerySessionStatus(const CdmSessionId& session_id,
                                              CdmQueryMap* key_info);
+  virtual bool IsReleaseSession(const CdmSessionId& session_id);
+  virtual bool IsOfflineSession(const CdmSessionId& session_id);
 
   // Query license information
   virtual CdmResponseType QueryKeyStatus(const CdmSessionId& session_id,
                                          CdmQueryMap* key_info);
 
-  // Query seesion control information
+  // Query session control information
   virtual CdmResponseType QueryKeyControlInfo(const CdmSessionId& session_id,
                                               CdmQueryMap* key_info);