Roll Perfetto from a962afa04fee to c50b1e5063fe (4 revisions)

https://android.googlesource.com/platform/external/perfetto.git/+log/a962afa04fee..c50b1e5063fe

2020-07-01 fmayer@google.com Merge "-Werror=global-constructors for heapprofd_client_api."
2020-07-01 lalitm@google.com Merge "tp: add small section on span join"
2020-07-01 fmayer@google.com Merge "Produce one pprof file per heap."
2020-07-01 lalitm@google.com tp: add link to internal metric documentation

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/perfetto-chromium-autoroll
Please CC perfetto-bugs@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/master/autoroll/README.md

Cq-Include-Trybots: luci.chromium.try:linux-perfetto-rel
Bug: None
Tbr: perfetto-bugs@google.com
Change-Id: I01a24122676cc0ead8f195f69df11ccae5a8f14d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2278005
Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#784473}