Use WebIDBKeyPath type in WebKit API, implement IndexedDBKeyPath type.

content/ppapi_plugin/ppapi_webkitplatformsupport_impl.h

Index: content/ppapi_plugin/ppapi_webkitplatformsupport_impl.h
diff --git a/content/ppapi_plugin/ppapi_webkitplatformsupport_impl.h b/content/ppapi_plugin/ppapi_webkitplatformsupport_impl.h
index 93a349df0bff8e7cd38030fc60507375257157cd..a548ad9f4350c3491b09c2344fe3e8dc3e7dbd78 100644
--- a/content/ppapi_plugin/ppapi_webkitplatformsupport_impl.h
+++ b/content/ppapi_plugin/ppapi_webkitplatformsupport_impl.h
@@ -50,12 +50,12 @@ class PpapiWebKitPlatformSupportImpl :
                                  bool sync_dir);
   virtual void createIDBKeysFromSerializedValuesAndKeyPath(
       const WebKit::WebVector<WebKit::WebSerializedScriptValue>& values,
-      const WebKit::WebString& keyPath,
+      const WebKit::WebIDBKeyPath& keyPath,
       WebKit::WebVector<WebKit::WebIDBKey>& keys);
   virtual WebKit::WebSerializedScriptValue injectIDBKeyIntoSerializedValue(
       const WebKit::WebIDBKey& key,
       const WebKit::WebSerializedScriptValue& value,
-      const WebKit::WebString& keyPath);
+      const WebKit::WebIDBKeyPath& keyPath);
 
  private:
   class SandboxSupport;