replace newly added OVERRIDE in content/

R=jochen@chromium.org,falken@chromium.org
BUG=417463

Review URL: https://codereview.chromium.org/653593003

Cr-Commit-Position: refs/heads/master@{#299418}

content/browser/service_worker/service_worker_dispatcher_host_unittest.cc

@@ -133,7 +133,7 @@ class ServiceWorkerTestContentBrowserClient : public TestContentBrowserClient {
   ServiceWorkerTestContentBrowserClient() {}
   virtual bool AllowServiceWorker(const GURL& scope,
                                   const GURL& first_party,
-                                  content::ResourceContext* context) OVERRIDE {
+                                  content::ResourceContext* context) override {
     return false;
   }
 };