Protocol handlers should be able to register a service worker.

content/public/browser/content_browser_client.cc

Index: content/public/browser/content_browser_client.cc
diff --git a/content/public/browser/content_browser_client.cc b/content/public/browser/content_browser_client.cc
index 01b58bd9d148828546b7e7c2fe3d810fa847e548..e212e3eabc5d26d1f500336dee07c5d4b99f5b86 100644
--- a/content/public/browser/content_browser_client.cc
+++ b/content/public/browser/content_browser_client.cc
@@ -65,6 +65,11 @@ bool ContentBrowserClient::IsHandledURL(const GURL& url) {
   return false;
 }
 
+GURL ContentBrowserClient::GetHandlerFor(BrowserContext* browser_context,
+    const GURL& url) {
+  return GURL::EmptyGURL();
+}
+
 bool ContentBrowserClient::CanCommitURL(RenderProcessHost* process_host,
                                         const GURL& site_url) {
   return true;