Add error detail metric to some session methods

[ Merge from http://go/wvgerrit/71726 ]

Adds an error detail metric attribute to RestoreUsageSession and
RestoreOfflineSession. These metrics will now report an additional
attribute providing additional error detail for debugging.

BUG: http://b/115517916

Test: CDM Unit Tests. Manually tried GPlay.

Change-Id: Ib48361ef29d33a16150473d8967e4850bc0c623d

libwvdrmengine/cdm/core/include/cdm_engine.h

@@ -225,14 +225,19 @@ class CdmEngine {
 
   // Usage related methods for streaming licenses
   // Retrieve a random usage info from the list of all usage infos for this app
-  // id.
+  // id. If |error_detail| is not null, an additional error code may be provided
+  // in the event of an error.
   virtual CdmResponseType GetUsageInfo(const std::string& app_id,
+                                       CdmResponseType* error_detail,
                                        CdmUsageInfo* usage_info);
 
   // Retrieve the usage info for the specified pst.
   // Returns UNKNOWN_ERROR if no usage info was found.
+  // id. If |error_detail| is not null, an additional error code may be provided
+  // in the event of an error.
   virtual CdmResponseType GetUsageInfo(const std::string& app_id,
                                        const CdmSecureStopId& ssid,
+                                       CdmResponseType* error_detail,
                                        CdmUsageInfo* usage_info);
 
   // Remove all usage records for the current origin.
@@ -358,6 +363,7 @@ class CdmEngine {
   bool ValidateKeySystem(const CdmKeySystem& key_system);
   CdmResponseType GetUsageInfo(const std::string& app_id,
                                SecurityLevel requested_security_level,
+                               CdmResponseType* error_detail,
                                CdmUsageInfo* usage_info);
 
   void OnKeyReleaseEvent(const CdmKeySetId& key_set_id);