Remove unused function ExtractValueType.
Remove unused function ExtractValueType.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=188728505

yuwolf/leveldb,dwing4g/leveldb,luke-jr/leveldb,fastogt/leveldb,dwing4g/leveldb,fuchsia-mirror/third_party-leveldb,cmumford/leveldb,dwing4g/leveldb,yuwolf/leveldb,bitcoin-core/leveldb,fuchsia-mirror/third_party-leveldb,bitcoin-core/leveldb,matehat/leveldb,yuwolf/leveldb,fastogt/leveldb,cmumford/leveldb,matehat/leveldb,matehat/leveldb,likema/leveldb,google/leveldb,luke-jr/leveldb,likema/leveldb,google/leveldb,bitcoin-core/leveldb