public GenericDraweeHierarchyBuilder setPlaceholderImage(
      Drawable placeholderDrawable, @Nullable ScalingUtils.ScaleType placeholderImageScaleType) {
    mPlaceholderImage = placeholderDrawable;
    mPlaceholderImageScaleType = placeholderImageScaleType;
    return this;
  }
Sets the placeholder image and its scale type.

@param placeholderDrawable drawable to be used as placeholder image
@param placeholderImageScaleType scale type for the placeholder image
@return modified instance of this builder
drawee/src/main/java/com/facebook/drawee/generic/GenericDraweeHierarchyBuilder.java