NetEq: Use TickTimer in DelayManager This change replaces packet_iat_count_ms_ and max_timer_ms_, two time-counting member variables in DelayManager, with Stopwatch objects obtained from a TickTimer. BUG=webrtc:5608 Review-Url: https://codereview.webrtc.org/1929863002 Cr-Original-Commit-Position: refs/heads/master@{#12554} Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc Cr-Mirrored-Commit: 8f8c96d1924c96f3a5c149ca31883d296ddceca7