Add Property to Access System ID

Adds a new property to the CDM's QueryStatus called QUERY_KEY_SYSTEM_ID that
contains the System ID. (as read from OEMCrypto_GetKeyData)  Adds a new
property to the DrmPlugin (cleverly named "systemId") that allows the app to
query for this.  Also adds unit tests.

Also changes the Device ID getter in crypto_engine.cpp to return a failure
instead of an empty ID.

Bug: 8621632

Merge of https://widevine-internal-review.googlesource.com/#/c/5010/ from
widevine cdm repository to android repository.

Change-Id: I8f309af18487c499e8ce25e829059e45623ea4dc

libwvdrmengine/cdm/core/src/cdm_engine.cpp

@@ -3,6 +3,7 @@
 #include "cdm_engine.h"
 
 #include <iostream>
+#include <sstream>
 
 #include "buffer_reader.h"
 #include "cdm_session.h"
@@ -315,7 +316,19 @@ CdmResponseType CdmEngine::QueryStatus(CdmQueryMap* key_info) {
       return KEY_ERROR;
   }
 
-  (*key_info)[QUERY_KEY_DEVICE_ID] = crypto_engine->GetDeviceUniqueId();
+  std::string deviceId;
+  bool success = crypto_engine->GetDeviceUniqueId(&deviceId);
+  if (success) {
+    (*key_info)[QUERY_KEY_DEVICE_ID] = deviceId;
+  }
+
+  uint32_t system_id;
+  success = crypto_engine->GetSystemId(&system_id);
+  if (success) {
+    std::ostringstream system_id_stream;
+    system_id_stream << system_id;
+    (*key_info)[QUERY_KEY_SYSTEM_ID] = system_id_stream.str();
+  }
 
   return NO_ERROR;
 }