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

third_party/WebKit/Source/web/WebSerializedScriptValueVersion.cpp

Index: third_party/WebKit/Source/web/WebSerializedScriptValueVersion.cpp
diff --git a/third_party/WebKit/Source/web/WebSerializedScriptValueVersion.cpp b/third_party/WebKit/Source/web/WebSerializedScriptValueVersion.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..9adfba5f780873e9feafe65256caf54c58302f66
--- /dev/null
+++ b/third_party/WebKit/Source/web/WebSerializedScriptValueVersion.cpp
@@ -0,0 +1,19 @@
+// Copyright 2017 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.
+
+#include "public/web/WebSerializedScriptValueVersion.h"
+
+#include "bindings/core/v8/SerializedScriptValue.h"
+
+namespace blink {
+
+WebSerializedScriptValueVersion WebSerializedScriptValueVersion::current() {
+  WebSerializedScriptValueVersion result;
+  // TODO(jbroman): Fetch the proper version from V8.
+  result.v8Version = 0;
+  result.blinkVersion = SerializedScriptValue::wireFormatVersion;
+  return result;
+}
+
+}  // namespace blink