Notify CloseFile from Pepper to FileSystem.

webkit/plugins/ppapi/mock_plugin_delegate.cc

Index: webkit/plugins/ppapi/mock_plugin_delegate.cc
diff --git a/webkit/plugins/ppapi/mock_plugin_delegate.cc b/webkit/plugins/ppapi/mock_plugin_delegate.cc
index b648e68c9feac1f5fbb018a120d5ccb8efbf4d2c..4a2f16d1dfb6bca6f443610cf2090a12f3ad8af6 100644
--- a/webkit/plugins/ppapi/mock_plugin_delegate.cc
+++ b/webkit/plugins/ppapi/mock_plugin_delegate.cc
@@ -142,6 +142,11 @@ bool MockPluginDelegate::AsyncOpenFileSystemURL(
   return false;
 }
 
+base::Callback<void (base::PlatformFileError)>
+MockPluginDelegate::GetCloseFileSystemURLCallback(const GURL& path) {
+  return base::Callback<void (base::PlatformFileError)>();
+}
+
 bool MockPluginDelegate::OpenFileSystem(
     const GURL& url,
     fileapi::FileSystemType type,