Trace PostTasks from post to run

ipc/ipc_message.h

Index: ipc/ipc_message.h
diff --git a/ipc/ipc_message.h b/ipc/ipc_message.h
index 3c629603ce3e8c3b7662680a74018143a41227aa..1ae9e759729d5b1991a8954b54fb8056fb217a62 100644
--- a/ipc/ipc_message.h
+++ b/ipc/ipc_message.h
@@ -224,9 +224,13 @@ class IPC_EXPORT Message : public Pickle {
   bool dont_log() const { return dont_log_; }
 #endif
 
-  // Called at various points between send and receive to track message.
-  void TraceMessageStep() {
-    TRACE_EVENT_ASYNC_STEP0("ipc", "IPC", header()->flags, "step");
+  // Called to trace when message is sent.
+  void TraceMessageBegin() {
+    TRACE_EVENT_FLOW_BEGIN0("ipc", "IPC", header()->flags);
+  }
+  // Called to trace when message is received.
+  void TraceMessageEnd() {
+    TRACE_EVENT_FLOW_END0("ipc", "IPC", header()->flags);
   }
 
  protected: