src: remove unused private data member

PR-URL: https://github.com/nodejs/node/pull/20974
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

src/tracing/node_trace_buffer.cc

@@ -88,7 +88,7 @@ void InternalTraceBuffer::ExtractHandle(
 
 NodeTraceBuffer::NodeTraceBuffer(size_t max_chunks,
     Agent* agent, uv_loop_t* tracing_loop)
-    : tracing_loop_(tracing_loop), agent_(agent),
+    : tracing_loop_(tracing_loop),
       buffer1_(max_chunks, 0, agent),
       buffer2_(max_chunks, 1, agent) {
   current_buf_.store(&buffer1_);

src/tracing/node_trace_buffer.h

@@ -72,7 +72,6 @@ class NodeTraceBuffer : public TraceBuffer {
   Mutex exit_mutex_;
   // Used to wait until async handles have been closed.
   ConditionVariable exit_cond_;
-  Agent* agent_;
   std::atomic<InternalTraceBuffer*> current_buf_;
   InternalTraceBuffer buffer1_;
   InternalTraceBuffer buffer2_;