transcoding: add SimulatedTranscoder to test service

- Add SimulatedTranscoder (which is an upgraded version of
  DummyTranscoder) to allow more testing of the service.

- Add unit test that launches dummy test apps from shell
  to simulate uid policy change.

bug: 154734285
bug: 145233472
test: unit tests

Change-Id: Ic169757d64ad8da7eebd0e1febdcbfb467fe81f4
diff --git a/media/libmediatranscoding/tests/TranscodingJobScheduler_tests.cpp b/media/libmediatranscoding/tests/TranscodingJobScheduler_tests.cpp
index 95edf1d..adb16a2 100644
--- a/media/libmediatranscoding/tests/TranscodingJobScheduler_tests.cpp
+++ b/media/libmediatranscoding/tests/TranscodingJobScheduler_tests.cpp
@@ -84,6 +84,8 @@
     virtual ~TestTranscoder() {}
 
     // TranscoderInterface
+    void setCallback(const std::shared_ptr<TranscoderCallbackInterface>& /*cb*/) override {}
+
     void start(int64_t clientId, int32_t jobId) override {
         mEventQueue.push_back(Start(clientId, jobId));
     }
@@ -157,6 +159,7 @@
     Status onTranscodingFinished(int32_t in_jobId,
                                  const TranscodingResultParcel& in_result) override {
         EXPECT_EQ(in_jobId, in_result.jobId);
+        ALOGD("TestClientCallback: received onTranscodingFinished");
         mOwner->onFinished(mClientId, in_jobId);
         return Status::ok();
     }