Enable dithering on RippleDrawable

Per UX request, given that gradients started to show some banding.

Test: manual
Fixes: 189281134
Change-Id: I8898f2463c6e07c390c07c242b6632dcbb9c3ef3

graphics/java/android/graphics/drawable/RippleDrawable.java

@@ -1193,6 +1193,9 @@ public class RippleDrawable extends LayerDrawable {
             mRipplePaint = new Paint();
             mRipplePaint.setAntiAlias(true);
             mRipplePaint.setStyle(Paint.Style.FILL);
+            if (mState.mRippleStyle == STYLE_PATTERNED) {
+                mRipplePaint.setDither(true);
+            }
         }
 
         final float x = mHotspotBounds.exactCenterX();