Restore KeyedServiceFactory diagnostics for context use-after-destroy.

extensions/browser/api/web_request/web_request_api.cc

 // Copyright (c) 2012 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 "extensions/browser/api/web_request/web_request_api.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 377 matching lines @@
     std::string event_name = kWebRequestEvents[i];
     event_router->RegisterObserver(this, event_name);
 
     // Also observe the corresponding webview event.
     event_name.replace(
         0, sizeof(kWebRequestEventPrefix) - 1, webview::kWebViewEventPrefix);
     event_router->RegisterObserver(this, event_name);
   }
 }
 
-WebRequestAPI::~WebRequestAPI() {
+WebRequestAPI::~WebRequestAPI() = default;
+
+void WebRequestAPI::Shutdown() {
   EventRouter::Get(browser_context_)->UnregisterObserver(this);
 }
 
 static base::LazyInstance<
     BrowserContextKeyedAPIFactory<WebRequestAPI>>::DestructorAtExit g_factory =
     LAZY_INSTANCE_INITIALIZER;
 
 // static
 BrowserContextKeyedAPIFactory<WebRequestAPI>*
 WebRequestAPI::GetFactoryInstance() {
@@ skipping 2023 matching lines @@
   // Since EventListeners are segmented by browser_context, check that
   // last, as it is exceedingly unlikely to be different.
   return extension_id == that.extension_id &&
          sub_event_name == that.sub_event_name &&
          web_view_instance_id == that.web_view_instance_id &&
          embedder_process_id == that.embedder_process_id &&
          browser_context == that.browser_context;
 }
 
 }  // namespace extensions