trace_events: adds a new trace_events api

Removes the requirement to use `--trace-events-enabled` to enable
trace events. Tracing is enabled automatically if there are any
enabled categories.

Adds a new `trace_events` module with an API for enabling/disabling
trace events at runtime without a command line flag.

```js
const trace_events = require('trace_events');
const categories = [ 'node.perf', 'node.async_hooks' ];
const tracing = trace_events.createTracing({ categories });
tracing.enable();
// do stuff
tracing.disable();
```

Multiple `Tracing` objects may exist and be enabled at any point
in time. The enabled trace event categories is the union of all
enabled `Tracing` objects and the `--trace-event-categories`
flag.

PR-URL: https://github.com/nodejs/node/pull/19803
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/test/parallel/test-trace-events-async-hooks.js b/test/parallel/test-trace-events-async-hooks.js
index 7fb11223c3..d3c5a0af5b 100644
--- a/test/parallel/test-trace-events-async-hooks.js
+++ b/test/parallel/test-trace-events-async-hooks.js
@@ -13,8 +13,7 @@ tmpdir.refresh();
 process.chdir(tmpdir.path);
 
 const proc = cp.spawn(process.execPath,
-                      [ '--trace-events-enabled',
-                        '--trace-event-categories', 'node.async_hooks',
+                      [ '--trace-event-categories', 'node.async_hooks',
                         '-e', CODE ]);
 
 proc.once('exit', common.mustCall(() => {