Add a test to cover service worker update codepath when extension is updated

extensions/browser/service_worker_manager.cc

Index: extensions/browser/service_worker_manager.cc
diff --git a/extensions/browser/service_worker_manager.cc b/extensions/browser/service_worker_manager.cc
index 16167d4e3d9cfa31b25e5602c9fbb32d4b68f1b3..ec879faa184f61e372e2605d95b9aea5df83f3a2 100644
--- a/extensions/browser/service_worker_manager.cc
+++ b/extensions/browser/service_worker_manager.cc
@@ -48,4 +48,20 @@ void ServiceWorkerManager::OnExtensionUninstalled(
       ->DeleteForOrigin(extension->url(), base::Bind(&EmptySuccessCallback));
 }
 
+void ServiceWorkerManager::OnExtensionWillBeInstalled(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    bool is_update,
+    bool from_ephemeral,
+    const std::string& old_name) {
+  if (is_update) {
+    // If |extension| is updated, then we need to fetch fresh ServiceWorker
+    // next time.
+    content::BrowserContext::GetStoragePartitionForSite(browser_context_,
+                                                        extension->url())
+        ->GetServiceWorkerContext()
+        ->SetForceUpdateOnPageLoadForOrigin(extension->url());
+  }
+}
+
 }  // namespace extensions