Dereferences use count of the key by dec_ref_counts and removes it from the cache when the reference count
reaches zero.
Special case is with dec_ref_counts is zero, in which case the key is removed regardless of the current reference count.
It's not an error when the key doesn't exist in the cache.
| this |
an CacheKeys |
| key |
a key to remove/dereference |
| dec_ref_counts |
reference counts to drop, 0 to remove it regardless of the current reference count |
| cancellable |
optional Cancellable object, or null |
|
Whether succeeded. |