Transcoder: Name transcoder threads for easier trace identification.

Bug: 183751395
Test: build_and_run_all_unit_tests.sh
Change-Id: I7b210d876584e3864540ba9991ed0e2a2de048e6
diff --git a/media/libmediatranscoding/transcoder/MediaSampleWriter.cpp b/media/libmediatranscoding/transcoder/MediaSampleWriter.cpp
index 10b2e80..d6ae0f3 100644
--- a/media/libmediatranscoding/transcoder/MediaSampleWriter.cpp
+++ b/media/libmediatranscoding/transcoder/MediaSampleWriter.cpp
@@ -20,6 +20,7 @@
 #include <android-base/logging.h>
 #include <media/MediaSampleWriter.h>
 #include <media/NdkMediaMuxer.h>
+#include <sys/prctl.h>
 
 namespace android {
 
@@ -173,6 +174,8 @@
 
     mState = STARTED;
     std::thread([this] {
+        prctl(PR_SET_NAME, (unsigned long)"SampleWriterTrd", 0, 0, 0);
+
         bool wasStopped = false;
         media_status_t status = writeSamples(&wasStopped);
         if (auto callbacks = mCallbacks.lock()) {