Merge "GpuService: add RootTargetPreparer to gpuservice_unittest" am: ced64f0280 am: 6b31f7bd91 am: 94cad7a5af am: 34fd400b1a

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/1475436

Change-Id: If7e72fc7239ff66d714d9e19538c1e1288c3d62f