[SyncFS] Support Delete operation on LevelDBWrapper::Iterator

chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc

Index: chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc
diff --git a/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc b/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc
index 3200b302366b4691d26c7741a93fb6deea69d4be..bf9c5e66cd8c3629013b03140ef4e581010d219b 100644
--- a/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc
+++ b/chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc
@@ -67,6 +67,18 @@ void LevelDBWrapper::Iterator::Next() {
   AdvanceIterators();
 }
 
+void LevelDBWrapper::Iterator::Delete() {
+  DCHECK(Valid());
+
+  const std::string key_str = key().ToString();
+  if (map_iterator_ != db_->pending_.end() && map_iterator_->first == key_str)
+    db_->pending_.erase(map_iterator_);
+  map_iterator_ = db_->pending_.insert(
+      std::make_pair(key_str,
+                     Transaction(DELETE_OPERATION, std::string()))).first;

[tzik, 2014/08/12 05:56:46]

Since we already have the right place to insert, how about doing like this?

Transaction deletion(DELETE_OPERATION, std::string());
std::pair<iterator, bool> inserted = db_->pending_.insert(map_iterator_,
std::make_pair(key_str, deletion));
map_iterator_ = inserted.first;
if (!inserted.second)
  map_iterator_->second = deletion;

[peria, 2014/08/12 06:04:34]

Done.

+  AdvanceIterators();
+}
+
 leveldb::Slice LevelDBWrapper::Iterator::key() {
   DCHECK(Valid());