[tracing] Avoid perfetto track aliasing in ['device/vr/openxr', 'third_party/blink/renderer/modules/xr'] [chromium/src : main]

[Etienne Pierre-Doray (Gerrit)]

Etienne Pierre-Doray has uploaded the change for review

Commit message

[tracing] Avoid perfetto track aliasing in ['device/vr/openxr', 'third_party/blink/renderer/modules/xr']

perfetto::Track::FromPointer is problematic because pointer reuse can
cause track aliasing in perfetto UI, leading to confusing traces (this
was true of legacy TRACE_EVENT_ASYNC as well).

To avoid these, we have the following alternatives:
1- Usin GetNextGlobalTraceId() instead of a pointer id to guarantee
  uniqueness. The track will get its name from the first event emitted.
2- Using NamedTrack to scope the pointer to a specific class
  (an aliased track would always correctly have the same name). This
  is more appropriate when there are several events emitted to the same
  track without a clear name. This has the benefit of giving the track
  a consistent, explicit name.
3- Replace custom track with "sync" instant events with flows.
  This reduces visual clutter and retain information about where
  events originated from.

This CL applies a migration to of one #1 or #2.

Questions for the reviewer:
- Design Fit: Is the choice of a dedicated async track (#1/#2)
  appropriate, or would is be suitable to emit "sync" events with
  flows (#3). As a rule of thumb, async tracks are appropriate to
  display a clear async operation (that could be recorded as UMA),
  or high level / user visible state.
- Naming: (when applicable) Is the track name I chose appropriate

This CL was uploaded by git cl split.

This CL was uploaded by git cl split.

Bug: 432427382

Change-Id: I097b9492ae1c15a2733de70d74db3fd99e0008b2

Change diff

Change information

Files:

• M device/vr/openxr/openxr_api_wrapper.cc
• M third_party/blink/renderer/modules/xr/xr_frame_provider.cc

Change size: S

Delta: 2 files changed, 11 insertions(+), 8 deletions(-)

Open in Gerrit

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Gerrit

Gerrit-MessageType: newchange

Gerrit-Project: chromium/src

Gerrit-Branch: main

Gerrit-Change-Id: I097b9492ae1c15a2733de70d74db3fd99e0008b2

Gerrit-Change-Number: 7871891

Gerrit-PatchSet: 1

Gerrit-Owner: Etienne Pierre-Doray <etie...@chromium.org>

Gerrit-Reviewer: Etienne Pierre-Doray <etie...@chromium.org>

Gerrit-CC: chromium...@chromium.org