Introduce ReferenceDelegates (#1222)

* Bump sequence number on resume token refresh

* Style

* Fix comment formatting

* Add FSTReferenceDelegate definition and documentation

* Add methods to return nil for delegates, wire up inMemoryPins

* Add hook for removing a reference

* Start work on reference delegates

* Fix up tests to support adding documents at a sequence number

* Implement removing references

* Remove from target when dropped from local view

* Fix warning

* Add hooks for removal from mutation queue

* Add hooks for limbo document updates

* Style

* Drop commented-out code

* Fixup after merging master

* Drop sequence number plumbing

* Style

* Drop errant semicolon

1 files changed, 1 insertions, 0 deletions

diff --git a/Firestore/Source/Local/FSTLevelDBMutationQueue.mm b/Firestore/Source/Local/FSTLevelDBMutationQueue.mm
index 75c3cf6..2c9f68d 100644
--- a/Firestore/Source/Local/FSTLevelDBMutationQueue.mm
+++ b/Firestore/Source/Local/FSTLevelDBMutationQueue.mm
@@ -511,6 +511,7 @@ using leveldb::WriteOptions;
                                              documentKey:mutation.key
                                                  batchID:batchID];
       _db.currentTransaction->Delete(key);
+      [_db.referenceDelegate removeMutationReference:mutation.key];
       [garbageCollector addPotentialGarbageKey:mutation.key];
     }
   }