Trace: don't identify Layout events just on name.

Because a `performance.measure('Layout')` would incorrectly be
identified, otherwise.

This is also the case for loads of events, but "Layout" is one that very
likely could be used by an end user for custom timings.

[email protected]

Bug: 434109012
Change-Id: Ic96eb2edc79e45d4f4ca9c2682c44aba6749a94f
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6811270
Commit-Queue: Paul Irish <[email protected]>
Commit-Queue: Jack Franklin <[email protected]>
Auto-Submit: Jack Franklin <[email protected]>
Reviewed-by: Paul Irish <[email protected]>

Author: jackfranklin

front_end/models/trace/types/TraceEvents.ts

@@ -1966,7 +1966,7 @@ export interface Layout extends Complete {
   };
 }
 export function isLayout(event: Event): event is Layout {
-  return event.name === Name.LAYOUT;
+  return event.name === Name.LAYOUT && Boolean(event.args && 'beginData' in event.args);
 }
 export interface InvalidateLayout extends Instant {
   name: Name.INVALIDATE_LAYOUT;