Merge "NetworkStats: more robust subtraction for deltas" am: be1e405cc7  -s ours am: 856ebe37eb  -s ours am: 5509ba6d40  -s ours
am: 62e276ef0b  -s ours

Change-Id: I4ee6fddf0ad34b24cb8de0606bf30a8ff4674c32