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/crypto_engine.cpp

@@ -5,6 +5,7 @@
 
 #include "crypto_engine.h"
 
+#include <arpa/inet.h>  // TODO(fredgc): Add ntoh to wv_cdm_utilities.h
 #include <iostream>
 #include <vector>
 
@@ -195,7 +196,7 @@ CryptoEngine::SecurityLevel CryptoEngine::GetSecurityLevel() {
   return kSecurityLevelUnknown;
 }
 
-std::string CryptoEngine::GetDeviceUniqueId() {
+bool CryptoEngine::GetDeviceUniqueId(std::string* deviceId) {
   std::vector<uint8_t> id;
   size_t idLength = 32;
 
@@ -204,10 +205,29 @@ std::string CryptoEngine::GetDeviceUniqueId() {
   OEMCryptoResult sts = OEMCrypto_GetDeviceID(&id[0], &idLength);
 
   if (OEMCrypto_SUCCESS != sts) {
-    return std::string();
+    return false;
   }
 
-  return std::string(reinterpret_cast<const char*>(&id[0]));
+  *deviceId = reinterpret_cast<const char*>(&id[0]);
+  return true;
+}
+
+bool CryptoEngine::GetSystemId(uint32_t* systemId) {
+  uint8_t buf[72];
+  size_t buflen = 72;
+
+  OEMCryptoResult sts = OEMCrypto_GetKeyData(buf, &buflen);
+
+  if (OEMCrypto_SUCCESS != sts) {
+    return false;
+  }
+
+  // Decode 32-bit int encoded as network-byte-order byte array starting at
+  // index 4.
+  uint32_t* id = reinterpret_cast<uint32_t*>(&buf[4]);
+
+  *systemId = ntohl(*id);
+  return true;
 }
 
 };  // namespace wvcdm