Steps to reproduce:
1. Open user attached project
2. Make sure that Preserve Framebuffer Alpha is enabled
3. Build & Run to an Android device
4. Observe that phone background is shown

Expected result: "Preserve framebuffer alpha" flag should render over native UI on Android.
Actual result: "Preserve framebuffer alpha" flag always shows the phone background

Reproduced in: 2019.1.0a13, 2018.3.0f2, 2017.4.18f1

Tested devices:
VLNQA00121, Samsung Galaxy S9 (SM-G960F), Android 8.0.0, CPU: Exynos 9 Series 9810, GPU: Mali-G72
VLNQA00138, Huawei P20 Pro (CLT-L29), Android 8.1.0, CPU: HiSilicon Kirin 970, GPU: Mali-G72
VLNQA00078, Motorola Nexus 6 (Nexus 6), Android 7.1.1, CPU: Snapdragon 805 APQ8084AB, GPU: Adreno (TM) 420