Steps to reproduce:
1. Open attached project "TimeDeltaTime2.zip"
2. Run on older Android OS (4.*~)
3. Lock screen while app is running
4. Leave it for a little while (15-30 minutes)
5. The delta time values will return negative values sometimes

Expected: delta time values return normal numbers, never negative
Actual: Sometimes the time is negative, which doesn't make sense. (The min: value on screen shows the minimum value of deltaTime recorded)

Reproduced on:
2018.1.0b8, 2017.3.1p1, 2017.2.1p4, 2017.2.0f1, 2017.2.0b1, 2017.2.0a3, 2017.2.0a2

On 2017.2.0a1 the project lags, akin to a repro, but the values are not displayed as negative, so not sure about this one.

No repro: 2017.1.3p1

Devices Under Test:
Motorola XT1021*, OS:4.4.4, CPU:armeabi-v7a, GPU:Adreno (TM) 305, Build:motorola/condor_retgb/condor_umts:4.4.4/KXC21.5-40/46:user/release-keys
(After a while the negative value can constantly be observed popping up)

Samsung GT S5310*, OS:4.1.2, CPU:armeabi-v7a, GPU:VideoCore IV HW, Build:samsung/corsicassxx/corsicass:4.1.2/JZO54K/S5310XXAME2:user/release-keys
(Repro, but the negative value was recorded and seldom shows up)

Htc HTC Desire 510*, OS:4.4.3, CPU:armeabi-v7a, GPU:Adreno (TM) 306, Build:htc/htc_europe/htc_a11ul:4.4.3/KTU84L/407309.7:user/release-keys
(NO REPRO)

Samsung SM G930F*, OS:7.0, CPU:arm64-v8a, GPU:Mali-T880, Build:samsung/heroltexx/herolte:7.0/NRD90M/G930FXXU1DQC4:user/release-keys
(NO REPRO)