cmd/trace/v2,internal/trace: use correct frame for identifying goroutines
To determine the identity of a goroutine for displaying in the trace UI,
we should use the root frame from a call stack. This will be the
starting function for the goroutine and is the same for each call stack
from a given goroutine. The new tracer no longer includes starting PCs
for goroutines which existed at the start of tracing, so we can't use a
PC for grouping together goroutines any more. Instead, we just use the
name of the entry function for grouping.
Fixes #65574
Change-Id: I5324653316f1acf0ab90c30680f181060ea45dd7
Reviewed-on: https://go-review.googlesource.com/c/go/+/562455 Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: David Chase <drchase@google.com>