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

content/browser/indexed_db/indexed_db_leveldb_coding.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_LEVELDB_CODING_H_
 #define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_LEVELDB_CODING_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 211 matching lines @@
   enum MetaDataType {
     ORIGIN_NAME = 0,
     DATABASE_NAME = 1,
     USER_VERSION = 2,
     MAX_OBJECT_STORE_ID = 3,
     USER_INT_VERSION = 4,
     BLOB_KEY_GENERATOR_CURRENT_NUMBER = 5,
     MAX_SIMPLE_METADATA_TYPE = 6
   };
 
-  static const int64 kAllBlobsKey = 1;
-  static const int64 kBlobKeyGeneratorInitialNumber = 2;
-  static const int64 kInvalidBlobKey = -1;  // All keys <= 0 are invalid.
+  static const int64 kAllBlobsKey;
+  static const int64 kBlobKeyGeneratorInitialNumber;
+  // All keys <= 0 are invalid.  This one's just a convenient example.
+  static const int64 kInvalidBlobKey;
 
   static bool IsValidBlobKey(int64 blobKey);
   CONTENT_EXPORT static std::string Encode(int64 database_id,
                                            MetaDataType type);
 };
 
 class ObjectStoreMetaDataKey {
  public:
   enum MetaDataType {
     NAME = 0,
@@ skipping 229 matching lines @@
   std::string encoded_user_key_;
   std::string encoded_primary_key_;
   int64 sequence_number_;
 
   DISALLOW_COPY_AND_ASSIGN(IndexDataKey);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_LEVELDB_CODING_H_