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

content/browser/tracing/tracing_controller_impl.h

Index: content/browser/tracing/tracing_controller_impl.h
diff --git a/content/browser/tracing/tracing_controller_impl.h b/content/browser/tracing/tracing_controller_impl.h
index 2ce1193885b471f14e951572837b568a78dacf70..3dc0b5aae40231c9b0af4d5422afdbc348ba4a4e 100644
--- a/content/browser/tracing/tracing_controller_impl.h
+++ b/content/browser/tracing/tracing_controller_impl.h
@@ -70,7 +70,7 @@ class TracingControllerImpl
   void StopAgentTracing(const StopAgentTracingCallback& callback) override;
   bool SupportsExplicitClockSync() override;
   void RecordClockSyncMarker(
-      int sync_id,
+      const std::string& sync_id,
       const RecordClockSyncMarkerCallback& callback) override;
 
   // base::trace_event::MemoryDumpManagerDelegate implementation.
@@ -182,11 +182,10 @@ class TracingControllerImpl
 
   void OnMonitoringStateChanged(bool is_monitoring);
 
-  int GetUniqueClockSyncID();
   // Issue clock sync markers to the tracing agents.
   void IssueClockSyncMarker();
   void OnClockSyncMarkerRecordedByAgent(
-      int sync_id,
+      const std::string& sync_id,
       const base::TimeTicks& issue_ts,
       const base::TimeTicks& issue_end_ts);