Merge "GpuService: add RootTargetPreparer to gpuservice_unittest" am: ced64f0280 am: 6b31f7bd91

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

Change-Id: I29cab3e715978b273c2439da88d270b6d01ca91f