Add IndexedDBBlobInfo class, to be used for IDB Blob support.

content/browser/indexed_db/indexed_db_leveldb_coding.cc

Index: content/browser/indexed_db/indexed_db_leveldb_coding.cc
diff --git a/content/browser/indexed_db/indexed_db_leveldb_coding.cc b/content/browser/indexed_db/indexed_db_leveldb_coding.cc
index 23766030407ea4a71d8c52f4849dc02616bd1e93..694bf6ea2a70e795ebad2da1a7dad549416f0e96 100644
--- a/content/browser/indexed_db/indexed_db_leveldb_coding.cc
+++ b/content/browser/indexed_db/indexed_db_leveldb_coding.cc
@@ -1400,6 +1400,10 @@ bool DatabaseMetaDataKey::IsValidBlobKey(int64 blob_key) {
   return blob_key >= kBlobKeyGeneratorInitialNumber;
 }
 
+const int64 DatabaseMetaDataKey::kAllBlobsKey = 1;
+const int64 DatabaseMetaDataKey::kBlobKeyGeneratorInitialNumber = 2;
+const int64 DatabaseMetaDataKey::kInvalidBlobKey = -1;
+
 std::string DatabaseMetaDataKey::Encode(int64 database_id,
                                         MetaDataType meta_data_type) {
   KeyPrefix prefix(database_id);