Update default CardView background colors to match the spec.

The spec states to use #FFF for light theme and #424242 for dark theme
card view backgrounds.

See https://www.google.com/design/spec/style/color.html#color-themes

Bug: 25765709
Change-Id: I6b432367416880d51d853788b6b14a7eb6d4ee01
1 file changed