[automerger skipped] [DO NOT MERGE] Refactor ViewScreenshotTestRule slightly...

[automerger skipped] [DO NOT MERGE] Refactor ViewScreenshotTestRule slightly to make it a bit extensible am: e861ada2 am: 6ffd6e9f -s ours am: 5cd555c6 -s ours am: a2eade35 -s ours

am skip reason: subject contains skip directive

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21931979



Change-Id: I68990572d3952bba31291d39d007e865a5dbb701
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>