Add `ToString()` to `LevelDbTransaction` (#946)

* Initial plumbing for leveldb local parts

* Add model::BatchId

* Port leveldb_key.{h,cc}

* Add string StartsWith

* Add leveldb_key_test.cc to the project

* Revert back to using leveldb::Slice for read/describe

These operations universally operate on keys obtained from leveldb so
it's actually unhelpful to force all the callers to make
absl::string_views from them.

* Start work on ToString for transactions

* Add ToString() method to LevelDbTransaction

* Style

* lint

* Revert addition of util::StartsWith

1 files changed, 2 insertions, 0 deletions

diff --git a/Firestore/core/src/firebase/firestore/local/leveldb_transaction.h b/Firestore/core/src/firebase/firestore/local/leveldb_transaction.h
index 015a6cb..b219a69 100644
--- a/Firestore/core/src/firebase/firestore/local/leveldb_transaction.h
+++ b/Firestore/core/src/firebase/firestore/local/leveldb_transaction.h
@@ -188,6 +188,8 @@ class LevelDbTransaction {
    */
   void Commit();
 
+  std::string ToString();
+
  private:
   leveldb::DB* db_;
   Mutations mutations_;