1901521 - [wpt-sync] Sync PR 46671 - compute pressure: Track client state in PressureObserverManager, rework PressureClientImpl::Reset()

Status: NEW

(Testing :: web-platform-tests, task, P4)

Description

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 46671 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/46671
Details from upstream follow.

Raphael Kubo da Costa <[e-mail]> wrote:

compute pressure: Track client state in PressureObserverManager, rework PressureClientImpl::Reset()

This solves two issues:

1. A design issue. PressureClientImpl::State represented a concept that
   only made sense in PressureObserverManager's context, so it should be
   tracked there.
   The different states concern whether WebPressureManager.AddClient()
   has been called for a given source type and whether it has finished
   running.

2. A bug. PressureClientImpl::Reset() was too eager and cleared too many
   variables:

   • Clearing |observers_| means PressureObserver instances would be
     left dangling and never receive any updates even if the given
     PressureClientImpl ended up connecting to the browser process.
   • Resetting |state_| caused PressureObserverManager::DidAddClient()
     to exit early in case the AddClient() handler in the browser
     process reset or dropped the pending PressureClient remote before
     sending back a PressureStatus.
     In this case, existing PressureObserver instances would never be
     notified and any pending promises would never be fulfilled or
     rejected.

Change-Id: Ia671bdbeb8067cb518111810a3281eaab1abdd1d
Reviewed-on: https://chromium-review.googlesource.com/5611240
WPT-Export-Revision: 51a886aeae3d8ac19377a4f4654076238c986d85