transcoding: Make TranscodingTestConfig to be nullable.

Bug: 145628554
Bug: 154734285
Test: Unit test
Change-Id: I93b5f6a34ad02d82f154d3ae07ed0516b1780db2
diff --git a/services/mediatranscoding/SimulatedTranscoder.cpp b/services/mediatranscoding/SimulatedTranscoder.cpp
index cdced2d..5aa325f 100644
--- a/services/mediatranscoding/SimulatedTranscoder.cpp
+++ b/services/mediatranscoding/SimulatedTranscoder.cpp
@@ -50,8 +50,8 @@
 void SimulatedTranscoder::start(
         ClientIdType clientId, JobIdType jobId, const TranscodingRequestParcel& request,
         const std::shared_ptr<ITranscodingClientCallback>& /*clientCallback*/) {
-    if (request.testConfig.processingTotalTimeMs > 0) {
-        mJobProcessingTimeMs = request.testConfig.processingTotalTimeMs;
+    if (request.testConfig.has_value() && request.testConfig->processingTotalTimeMs > 0) {
+        mJobProcessingTimeMs = request.testConfig->processingTotalTimeMs;
     }
     ALOGV("%s: job {%d}: processingTime: %lld", __FUNCTION__, jobId,
           (long long)mJobProcessingTimeMs);