SF: Update Layer::setBackgroundColor to use the factory interface

Rather than directly creating a ColorLayer, use the factory interface to
do so.  This allows an override to be created instead if desired.

Test: atest CtsViewTestCases
Test: go/wm-smoke
Bug: 121291683
Change-Id: I53f65f482bc896cb54857d6f268c550fd173f6ff
1 file changed