The FixedGainController is used in two places. One is the AudioMixer. There it's used to limit the audio level after adding streams. The other is GainController2, where it's placed after steps that could boost the audio level outside the allowed range. We log metrics from the FGC. To avoid confusion, this CL makes the two use cases log to different histograms. Chromium histogram CL is https://chromium-review.googlesource.com/c/chromium/src/+/1170833 Bug: webrtc:7494 Change-Id: I1abe60fd8e96556f144d2ee576254b15beca1174 Reviewed-on: https://webrtc-review.googlesource.com/93464 Commit-Queue: Alex Loiko <aleloi@webrtc.org> Reviewed-by: Ivo Creusen <ivoc@webrtc.org> Reviewed-by: Åsa Persson <asapersson@webrtc.org> Cr-Commit-Position: refs/heads/master@{#24284}