SF: Save proto traces to a specific path

Test: presubmit
Bug: 200284593

Change-Id: I6987329cc32b2ca13e76e957a5ae6b17bbed6e83
diff --git a/services/surfaceflinger/Tracing/TransactionTracing.cpp b/services/surfaceflinger/Tracing/TransactionTracing.cpp
index 298e63a..d5e837f 100644
--- a/services/surfaceflinger/Tracing/TransactionTracing.cpp
+++ b/services/surfaceflinger/Tracing/TransactionTracing.cpp
@@ -99,11 +99,11 @@
     writeToFile();
 }
 
-status_t TransactionTracing::writeToFile() {
+status_t TransactionTracing::writeToFile(std::string filename) {
     std::scoped_lock lock(mTraceLock);
     proto::TransactionTraceFile fileProto = createTraceFileProto();
     addStartingStateToProtoLocked(fileProto);
-    return mBuffer.writeToFile(fileProto, FILE_NAME);
+    return mBuffer.writeToFile(fileProto, filename);
 }
 
 void TransactionTracing::setBufferSize(size_t bufferSizeInBytes) {