@Nullable
  private Drawable buildBranch(
      @Nullable Drawable drawable, @Nullable ScalingUtils.ScaleType scaleType) {
    drawable = WrappingUtils.maybeApplyLeafRounding(drawable, mRoundingParams, mResources);
    drawable = WrappingUtils.maybeWrapWithScaleType(drawable, scaleType);
    return drawable;
  }
Applies scale type and rounding (both if specified).
drawee/src/main/java/com/facebook/drawee/generic/GenericDraweeHierarchy.java