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

extensions/browser/service_worker_manager.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/macros.h"
 #include "base/scoped_observer.h"
 #include "extensions/browser/extension_registry_observer.h"
 
 namespace content {
 class BrowserContext;
@@ skipping 10 matching lines @@
   ~ServiceWorkerManager() override;
 
  private:
   // ExtensionRegistryObserver:
   void OnExtensionUnloaded(content::BrowserContext* browser_context,
                            const Extension* extension,
                            UnloadedExtensionInfo::Reason reason) override;
   void OnExtensionUninstalled(content::BrowserContext* browser_context,
                               const Extension* extension,
                               extensions::UninstallReason reason) override;
+  void OnExtensionWillBeInstalled(content::BrowserContext* browser_context,
+                                  const Extension* extension,
+                                  bool is_update,
+                                  bool from_ephemeral,
+                                  const std::string& old_name) override;
 
   content::BrowserContext* browser_context_;
 
   ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
       registry_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerManager);
 };
 
 }  // namespace extensions