chromeos: Avoid DCHECK in ProxyResolutionServiceProvider.

chromeos/dbus/services/proxy_resolution_service_provider.h

 // 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.
 
 #ifndef CHROMEOS_DBUS_SERVICES_PROXY_RESOLUTION_SERVICE_PROVIDER_H_
 #define CHROMEOS_DBUS_SERVICES_PROXY_RESOLUTION_SERVICE_PROVIDER_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 85 matching lines @@
   // Called when ResolveProxy() is exported as a D-Bus method.
   void OnExported(const std::string& interface_name,
                   const std::string& method_name,
                   bool success);
 
   // Callback invoked when Chrome OS clients send network proxy resolution
   // requests to the service. Called on UI thread.
   void ResolveProxy(dbus::MethodCall* method_call,
                     dbus::ExportedObject::ResponseSender response_sender);
 
+  // Callback passed to network thread static methods to run
+  // NotifyProxyResolved() on |origin_thread_|.
+  using NotifyCallback = base::Callback<void(std::unique_ptr<Request>)>;
+
   // Helper method for ResolveProxy() that runs on network thread.
-  void ResolveProxyOnNetworkThread(std::unique_ptr<Request> request);
+  static void ResolveProxyOnNetworkThread(
+      std::unique_ptr<Request> request,
+      scoped_refptr<base::SingleThreadTaskRunner> notify_thread,
+      NotifyCallback notify_callback);

[James Cook, 2017/04/03 15:30:23]

I really appreciate your consistent naming of things like notify_*.

 
   // Callback on network thread for when net::ProxyService::ResolveProxy()
   // completes, synchronously or asynchronously.
-  void OnResolutionComplete(std::unique_ptr<Request> request, int result);
+  static void OnResolutionComplete(
+      std::unique_ptr<Request> request,
+      scoped_refptr<base::SingleThreadTaskRunner> notify_thread,
+      NotifyCallback notify_callback,
+      int result);
 
   // Called on UI thread from OnResolutionComplete() to pass the resolved proxy
   // information to the client over D-Bus.
   void NotifyProxyResolved(std::unique_ptr<Request> request);
 
   std::unique_ptr<Delegate> delegate_;
   scoped_refptr<dbus::ExportedObject> exported_object_;
   scoped_refptr<base::SingleThreadTaskRunner> origin_thread_;
   base::WeakPtrFactory<ProxyResolutionServiceProvider> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyResolutionServiceProvider);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_SERVICES_PROXY_RESOLUTION_SERVICE_PROVIDER_H_