Fix bug where status bar was not set properly.

- Need to check both alpha of the view, and alpha of the background color.

Bug: 187467559
Test: check status bar colors when using:
      - on white wallpaper,
      - on black wallpaper,
      - on wallpaper with white text
      - on wallpaper with dark text

Change-Id: Ie6f34d34dfa9dea716f95bd6a95125fbd650fc29