Enable pixel average in Material U simulation.

In a screenshot, the colors of borders might be vague and these colors
might be a little different from one another. Especially for dark
themes, borders would look very weird if both inside/outside the borders
are dark. This CL enables some pixel average techniques to make borders
look more reasonable.

Test: atest -c SystemUIGoogleRoboRNGTests
Change-Id: I2ae4e6f761838a5a971d6d84e615cb45e0837167
2 files changed