Improve support for dark theme

Update colors and styles to work well in dark mode,
and refactor wallpaper preview to update the header text
based on the wallpaper content.

Bug: 123432343

Change-Id: I409ee1c9e5c19072a7f296033a43454262c8077f
8 files changed
tree: 14b32af07e52e0d691a315d3dba34ffa1262c41a
  1. res/
  2. src/
  3. src_override/
  4. Android.mk
  5. AndroidManifest.xml