Use a two-part data format version in IndexedDB metadata.

content/browser/indexed_db/indexed_db_factory.h

Index: content/browser/indexed_db/indexed_db_factory.h
diff --git a/content/browser/indexed_db/indexed_db_factory.h b/content/browser/indexed_db/indexed_db_factory.h
index 40f2d64c5ba3c5aa7f22bb26dc4a94d0389c135a..f6a73e0ed2e36a9637b21e206092c060155285ce 100644
--- a/content/browser/indexed_db/indexed_db_factory.h
+++ b/content/browser/indexed_db/indexed_db_factory.h
@@ -31,6 +31,7 @@ class URLRequestContextGetter;
 namespace content {
 
 class IndexedDBBackingStore;
+class IndexedDBDataFormatVersion;
 struct IndexedDBPendingConnection;
 struct IndexedDBDataLossInfo;
 
@@ -48,13 +49,15 @@ class CONTENT_EXPORT IndexedDBFactory
       scoped_refptr<IndexedDBCallbacks> callbacks,
       const url::Origin& origin,
       const base::FilePath& data_directory,
+      const IndexedDBDataFormatVersion& client_data_format_version,
       scoped_refptr<net::URLRequestContextGetter> request_context_getter) = 0;
   virtual void Open(
       const base::string16& name,
       std::unique_ptr<IndexedDBPendingConnection> connection,
       scoped_refptr<net::URLRequestContextGetter> request_context_getter,
       const url::Origin& origin,
-      const base::FilePath& data_directory) = 0;
+      const base::FilePath& data_directory,
+      const IndexedDBDataFormatVersion& client_data_format_version) = 0;
 
   virtual void DeleteDatabase(
       const base::string16& name,
@@ -62,6 +65,7 @@ class CONTENT_EXPORT IndexedDBFactory
       scoped_refptr<IndexedDBCallbacks> callbacks,
       const url::Origin& origin,
       const base::FilePath& data_directory,
+      const IndexedDBDataFormatVersion& client_data_format_version,
       bool force_close) = 0;
 
   virtual void HandleBackingStoreFailure(const url::Origin& origin) = 0;
@@ -96,6 +100,7 @@ class CONTENT_EXPORT IndexedDBFactory
   virtual scoped_refptr<IndexedDBBackingStore> OpenBackingStore(
       const url::Origin& origin,
       const base::FilePath& data_directory,
+      const IndexedDBDataFormatVersion& client_data_format_version,
       scoped_refptr<net::URLRequestContextGetter> request_context_getter,
       IndexedDBDataLossInfo* data_loss_info,
       bool* disk_full,
@@ -104,6 +109,7 @@ class CONTENT_EXPORT IndexedDBFactory
   virtual scoped_refptr<IndexedDBBackingStore> OpenBackingStoreHelper(
       const url::Origin& origin,
       const base::FilePath& data_directory,
+      const IndexedDBDataFormatVersion& client_data_format_version,
       scoped_refptr<net::URLRequestContextGetter> request_context_getter,
       IndexedDBDataLossInfo* data_loss_info,
       bool* disk_full,