Revert 155974 "Cleanup the ScrollbarTheme classes."

> Cleanup the ScrollbarTheme classes.
>
> 1) Make all filenames consistent with their filenames.
> 2) Move all files into the core/platform directory out of the
> chromium and mac directories.
> 3) Remove Chromium from filenames.
> 4) Draw an inheritance diagram in ScrollbarTheme.h since it's complicated
> and there are so many files.
>
> BUG=None
>
> Review URL: https://chromiumcodereview.appspot.com/22754004

Broke android build

TBR=tony@chromium.org
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/23003002

git-svn-id: svn://svn.chromium.org/blink/trunk@155978 bbb929c8-8fbe-4397-9dbb-9b2b20218538