Add ref count to service workers for extension API.

extensions/browser/extension_util.h

Index: extensions/browser/extension_util.h
diff --git a/extensions/browser/extension_util.h b/extensions/browser/extension_util.h
index cdd4218ad14be242f26dc0ff866b0640bb9e7786..b3e823350c4a74fa61713054ff92868ebdc73bda 100644
--- a/extensions/browser/extension_util.h
+++ b/extensions/browser/extension_util.h
@@ -11,6 +11,7 @@ class GURL;
 
 namespace content {
 class BrowserContext;
+class StoragePartition;
 }
 
 namespace extensions {
@@ -34,6 +35,10 @@ bool SiteHasIsolatedStorage(const GURL& extension_site_url,
 // Returns true if the extension can be enabled in incognito mode.
 bool CanBeIncognitoEnabled(const Extension* extension);
 
+content::StoragePartition* GetStoragePartitionForExtensionId(
+    const std::string& extension_id,
+    content::BrowserContext* browser_context);
+
 }  // namespace util
 }  // namespace extensions