This makes it a bit more clear that values of member variables of
SourceFrame are never directly changed and that doing so is not an
intentional part of the design. Also made use of `SourceFrame` vs
`const SourceFrame` more consistent since the audio frame of a
`const SourceFrame` was being modified in some places.
Accessing the embedded AudioFrame can be done via the const
audio_frame() accessor or via the mutable_audio_frame() accessor when
modifying the frame is needed. This helps with clarifying later on
when downstream code paths such as ones that access the `packet_infos_`
data, can know that it won't be modified for the rest of the frame's
lifetime (thus avoiding having to make copies).
Bug: none
Change-Id: I175cec8fcdb85063239a5f9c299b7878c639f00e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/302383
Reviewed-by: Sam Zackrisson <saza@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39926}
683f3165f9