commit 3d7137f54f9d915b317aeb5d3f61ba24db099afb
author Tommi <tommi@webrtc.org> Fri Oct 17 11:38:22 2025
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Oct 17 13:09:38 2025
tree 9fd93551aecb8b83bc78feedc495d0bc9a52075d
parent 02acc3ded1ae87086fc2964b84d1ab9a8abe7433

Introduce MediaEngineReference for managing access on the worker thread

This encapsulates direct, non-const, access to the media engine and the
reference counting via a new class, MediaEngineReference.

This change introduces `ConnectionContext::MediaEngineReference`, a new
RAII wrapper class to manage the media engine's lifetime and access.

The `MediaEngineReference` class:
* Automatically handles reference counting in its constructor
    and destructor.
* Provides a `media_engine()` accessor that `DCHECK`s the call
    is on the worker thread, centralizing thread-safety enforcement.

`PeerConnection`, `PeerConnectionFactory` (for AEC dumps), and
`RtpTransceiver` are all updated to use `MediaEngineReference` instead
of calling the manual ref-counting methods.

Additionally, a new `ConnectionContext::is_configured_for_media()`
method is introduced to replace checks for `context_->media_engine()`
when determining if media is enabled.

This is a follow up to recent media engine changes that more tightly
control the lifetime of the media engine as well as divide access to
const and non-const methods. A follow up to this CL could be to split up
the media engine interfaces to make the actual work that runs on the
worker thread be owned by a separate interface from the const methods.
Then there'd be no need for the Init/Terminate methods and the design
would be a bit clearer.

Bug: webrtc:42224720
Change-Id: Idd7bd9a143ee00d1939f0bac93c877253ac57e09
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/410922
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Reviewed-by: Markus Handell <handellm@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#45971}