Fix classes that have too many virtuals for inline constructors.

content/browser/service_worker/service_worker_context_observer.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CONTEXT_OBSERVER_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CONTEXT_OBSERVER_H_
 
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "content/browser/service_worker/service_worker_version.h"
@@ skipping 67 matching lines @@
   virtual void OnRegistrationDeleted(int64 registration_id,
                                      const GURL& pattern) {}
   virtual void OnForceUpdateOnPageLoadChanged(int64 registration_id,
                                               bool force_update_on_page_load) {}
 
   // Notified when the storage corruption recovery is completed and all stored
   // data is wiped out.
   virtual void OnStorageWiped() {}
 
  protected:
+  ServiceWorkerContextObserver() = default;
   virtual ~ServiceWorkerContextObserver() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CONTEXT_OBSERVER_H_