Record DevTools metadata events on worker threads when starting recoring tracing based Timeline

Source/core/workers/WorkerGlobalScopeProxy.h

Index: Source/core/workers/WorkerGlobalScopeProxy.h
diff --git a/Source/core/workers/WorkerGlobalScopeProxy.h b/Source/core/workers/WorkerGlobalScopeProxy.h
index bfcb169722bed4f91117ad85bb7e56ff83797a97..162dfb53dd766d7bc858c458ecf578100314516e 100644
--- a/Source/core/workers/WorkerGlobalScopeProxy.h
+++ b/Source/core/workers/WorkerGlobalScopeProxy.h
@@ -64,6 +64,7 @@ namespace blink {
         virtual void connectToInspector(PageInspector*) { }
         virtual void disconnectFromInspector() { }
         virtual void sendMessageToInspector(const String&) { }
+        virtual void writeTimelineStartedEvent(const String& sessionId) { }
     };
 
 } // namespace blink