Android 10 gestural navigation, edge back gesture

edge back function was enabled in this file frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/EdgeBackGestureHandler.java

https://cs.android.com/android/platform/superproject/+/master:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/EdgeBackGestureHandler.java;l=253;bpv=0;bpt=1