@VisibleForTesting
  synchronized void trimToSoftCap() {
    if (isMaxSizeSoftCapExceeded()) {
      trimToSize(mPoolParams.maxSizeSoftCap);
    }
  }
Trim the (free portion of the) pool so that the pool size is at or below the soft cap. This
will try to free up values in the free portion of the pool, until (a) the pool size is now
below the soft cap configured OR (b) the free portion of the pool is empty
imagepipeline/src/main/java/com/facebook/imagepipeline/memory/BasePool.java