This reduces jitter in the WifiTracker and is modeled after a prior broken implementation which attempted to half-life the rssi each time AccessPoint.update(ScanResult) is called. Bug: 34774783 Test: runtest --path frameworks/base/packages/SettingsLib/tests/integ/src/com/android/settingslib/wifi/AccessPointTest.java Change-Id: Iab3f9914af40f2fd56e8ae7b45dcbd62176c8a67