[Tracing] Update sync_id to be string type for clock sync

base/trace_event/tracing_agent.cc

Index: base/trace_event/tracing_agent.cc
diff --git a/base/trace_event/tracing_agent.cc b/base/trace_event/tracing_agent.cc
index 3c95a3d63ca04fa0033d34019a78c59e27bc7785..0af90f3c7243655722c3bcea01891d6590f7293a 100644
--- a/base/trace_event/tracing_agent.cc
+++ b/base/trace_event/tracing_agent.cc
@@ -14,7 +14,7 @@ bool TracingAgent::SupportsExplicitClockSync() {
 }
 
 void TracingAgent::RecordClockSyncMarker(
-    int sync_id,
+    const std::string& sync_id,
     const RecordClockSyncMarkerCallback& callback) {
   DCHECK(SupportsExplicitClockSync());
 }