Revert "Implement scrim method"

This reverts commit d849ef08.

Reason for revert: not needed

I was too eager to merge this CL. It turns out all I need is these
three constants and doesn't actually need the aidl change.

public static final int MAIN_COLOR_LIGHT = 0xffdadce0;
public static final int MAIN_COLOR_DARK = 0xff202124;
public static final int MAIN_COLOR_REGULAR = 0xff000000;

Change-Id: Iafd539a06455ba0878a6d3750f3c7194f8919fbf