This a part of the new Filestore management capabilities which is configurable with the binarystore.xml configuration file. Here you can find more details on the subject.
The default chain when using google-storage as a binary provider is the following:
<provider id="cache-fs" type="cache-fs">
<provider id="eventual" type="eventual">
<provider id="retry" type="retry">
<provider id="google-storage" type="google-storage"/>
Here is an example configuration part for the google-storage:
<provider id="google-storage" type="google-storage">
Here are additional parameters which can be configured for google-storage.