Specifying guards for functions and member variables. Also updating
a few places for VideoReceiveStream2 accordingly.
Bug: webrtc:11993
Change-Id: I2d13b009ec9853c6b2d90b08af555ecdd2b1ced6
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/220765
Commit-Queue: Tommi <tommi@webrtc.org>
Reviewed-by: Markus Handell <handellm@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34174}