Implement async version of WebFileSystem::createFileWriter

content/child/fileapi/webfilesystem_impl.h

Index: content/child/fileapi/webfilesystem_impl.h
diff --git a/content/child/fileapi/webfilesystem_impl.h b/content/child/fileapi/webfilesystem_impl.h
index 2bcf535c1d83157365bf990881b35c1fbbcf0a5e..6ca0c5b83d13f90013465a5f00ae4bf6c1589bd9 100644
--- a/content/child/fileapi/webfilesystem_impl.h
+++ b/content/child/fileapi/webfilesystem_impl.h
@@ -59,6 +59,10 @@ class WebFileSystemImpl : public WebKit::WebFileSystem {
       WebKit::WebFileSystemCallbacks*) OVERRIDE;
   virtual WebKit::WebFileWriter* createFileWriter(
       const WebKit::WebURL& path, WebKit::WebFileWriterClient*) OVERRIDE;
+  virtual void createFileWriter(
+      const WebKit::WebURL& path,
+      WebKit::WebFileWriterClient*,
+      WebKit::WebFileSystemCallbacks*) OVERRIDE;
   virtual void createSnapshotFileAndReadMetadata(
       const WebKit::WebURL& path,
       WebKit::WebFileSystemCallbacks*);