Keep disabled FastBitmapDrawables disabled while fast scrolling.

Previously, they were animating to be colored because they were
set to have a FAST_SCROLL_UNLHIGHLIGHTED state. Now they retain
their disabled color when changing fast scroll states.

Specfically, we remove the DISABLED state and instead make it a
property of the FastBitmapDrawable.

Bug: 32642959
Change-Id: I6cb2da134a550c267eebfc756eff8c91a33f028c
diff --git a/src/com/android/launcher3/PreloadIconDrawable.java b/src/com/android/launcher3/PreloadIconDrawable.java
index 8295b45..efc0eac 100644
--- a/src/com/android/launcher3/PreloadIconDrawable.java
+++ b/src/com/android/launcher3/PreloadIconDrawable.java
@@ -177,10 +177,8 @@
             // Set the paint color only when the level changes, so that the dominant color
             // is only calculated when needed.
             mPaint.setColor(getIndicatorColor());
-        }
-        if (mIcon instanceof FastBitmapDrawable) {
-            ((FastBitmapDrawable) mIcon).setState(level <= 0 ?
-                    FastBitmapDrawable.State.DISABLED : FastBitmapDrawable.State.NORMAL);
+        } else if (mIcon instanceof FastBitmapDrawable) {
+            ((FastBitmapDrawable) mIcon).setIsDisabled(true);
         }
 
         invalidateSelf();