Remote Assistance on Chrome OS Part III - NativeMessageHost

extensions/browser/api/messaging/native_message_host.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 EXTENSIONS_BROWSER_API_MESSAGING_NATIVE_MESSAGE_HOST_H_
+#define EXTENSIONS_BROWSER_API_MESSAGING_NATIVE_MESSAGE_HOST_H_
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "ui/gfx/native_widget_types.h"
+
+class PrefService;
+
+namespace extensions {
+
+// An interface for receiving messages from MessageService (Chrome) using the
+// Native Messaging API.  A NativeMessageHost object hosts a native component,
+// which can run in the browser-process or in a separate process (SEe

[Sergey Ulanov, 2014/09/25 01:45:22]

typo: SEe

[kelvinp, 2014/09/26 18:12:27]

Done.

+// NativeMessageProcessHost).
+class NativeMessageHost {
+ public:
+  // Callback interface for receiving messages from the native component. It is
+  // implemented by MessageService.
+  class Client {
+   public:
+    virtual ~Client() {}
+
+    // Called on the UI thread.
+    virtual void PostMessageFromNativeHost(int port_id,
+                                           const std::string& message) = 0;
+    virtual void CloseChannel(int port_id,
+                              const std::string& error_message) = 0;
+  };
+
+  // Creates the NativeMessageHost based on the |native_host_name|.
+  static scoped_ptr<NativeMessageHost> Create(
+      gfx::NativeView native_view,
+      base::WeakPtr<Client> client,
+      const std::string& source_extension_id,
+      const std::string& native_host_name,
+      int destination_port,

[Sergey Ulanov, 2014/09/25 01:45:22]

It looks wrong that the host implementation have to care about port ids, which
is an implementation detail of the MessageService. I suggest replacing Client
interface with two base::Callback<> parameters. This would allow you to curry
the port_id when creating the callbacks in MessagingService will not need to
expose them outside.

[kelvinp, 2014/09/26 18:12:27]

Done.

+      bool allow_user_level);
+
+  // Sends a message to the native component with the specified payload.
+  virtual void Send(const std::string& json) = 0;
+
+  virtual ~NativeMessageHost() {}

[Sergey Ulanov, 2014/09/25 01:45:22]

destructor should be declared between static methods and all other methods, i.e.
between Create() and Send().

[kelvinp, 2014/09/26 18:12:27]

Done.

+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_API_MESSAGING_NATIVE_MESSAGE_HOST_H_