[IndexedDB] Adding txn, value, and key size metrics

content/browser/indexed_db/indexed_db_backing_store.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_BACKING_STORE_H_
 #define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_BACKING_STORE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 151 matching lines @@
         std::vector<std::unique_ptr<storage::BlobDataHandle>>* handles);
     void PutBlobInfo(
         int64_t database_id,
         int64_t object_store_id,
         const std::string& object_store_data_key,
         std::vector<IndexedDBBlobInfo>*,
         std::vector<std::unique_ptr<storage::BlobDataHandle>>* handles);
 
     LevelDBTransaction* transaction() { return transaction_.get(); }
 
+    virtual uint64_t GetTransactionSize();
+
     leveldb::Status GetBlobInfoForRecord(
         int64_t database_id,
         const std::string& object_store_data_key,
         IndexedDBValue* value);
 
     // This holds a BlobEntryKey and the encoded IndexedDBBlobInfo vector stored
     // under that key.
     typedef std::vector<std::pair<BlobEntryKey, std::string> >
         BlobEntryKeyValuePairVec;
 
@@ skipping 511 matching lines @@
   // complete. While > 0, temporary journal entries may exist so out-of-band
   // journal cleaning must be deferred.
   size_t committing_transaction_count_;
 
   DISALLOW_COPY_AND_ASSIGN(IndexedDBBackingStore);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_BACKING_STORE_H_