Standardize usage of virtual/override/final specifiers in content/.

content/browser/service_worker/service_worker_version_unittest.cc

Index: content/browser/service_worker/service_worker_version_unittest.cc
diff --git a/content/browser/service_worker/service_worker_version_unittest.cc b/content/browser/service_worker/service_worker_version_unittest.cc
index a479f68b91a813967019ff3f35c991b8fe86607e..40115716a72512acd92acf5ded87ebbef8ae7b0f 100644
--- a/content/browser/service_worker/service_worker_version_unittest.cc
+++ b/content/browser/service_worker/service_worker_version_unittest.cc
@@ -179,7 +179,7 @@ class ServiceWorkerFailToStartTest : public ServiceWorkerVersionTest {
   ServiceWorkerFailToStartTest()
       : ServiceWorkerVersionTest() {}
 
-  virtual scoped_ptr<MessageReceiver> GetMessageReceiver() override {
+  scoped_ptr<MessageReceiver> GetMessageReceiver() override {
     return make_scoped_ptr(new MessageReceiverDisallowStart());
   }