Fix and cleanup UI rendering CTS tests


- Heighten tolerance on clipping tests, (as they're just testing for
  area, not color perfection)

- Reduce logspam during severe failures

- Put SW layer on content view, to guarantee it's never larger than
  the screen size

- Log when a bitmap is solid color, for easier debugging

Change-Id: I1357fe5e6c00fe8674e0fd450adcb9e5548203ee
10 files changed