Reason for revert: Breaks downstream projects: error: undefined reference to 'rtc::ExpFilter::kValueUndefined' error: undefined reference to 'rtc::ExpFilter::Apply(float, float)' error: undefined reference to 'rtc::ExpFilter::Reset(float)' rror: undefined reference to 'rtc::ExpFilter::UpdateBase(float)' Original issue's description: > Move smoothing filter to common audio. > > This will make the smoothing filter a basic tool that is going to be used by both voice engine and ANA. > > BUG=webrtc:6443 > > Committed: https://crrev.com/a82395bf7cd15b7396456df06fe952ede8db0c39 > Cr-Commit-Position: refs/heads/master@{#15146} TBR=minyue@webrtc.org,solenberg@webrtc.org,perkj@webrtc.org,tommi@webrtc.org,michaelt@webrtc.org # Skipping CQ checks because original CL landed less than 1 days ago. NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true BUG=webrtc:6443 Review-Url: https://codereview.webrtc.org/2510373002 Cr-Commit-Position: refs/heads/master@{#15147}