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/single_thread_task_runner.h"
+#include "ui/gfx/native_widget_types.h"
+
+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
+// NativeMessageProcessHost).
+class NativeMessageHost {
+ public:
+  // Callback interface for receiving messages from the native host.
+  class Client {
+   public:
+    virtual ~Client() {}
+
+    // Called on the UI thread.
+    virtual void PostMessageFromNativeHost(const std::string& message) = 0;
+    virtual void CloseChannel(const std::string& error_message) = 0;
+  };
+
+  // Creates the NativeMessageHost based on the |native_host_name|.
+  static scoped_ptr<NativeMessageHost> Create(
+      gfx::NativeView native_view,
+      const std::string& source_extension_id,
+      const std::string& native_host_name,
+      bool allow_user_level);
+
+  virtual ~NativeMessageHost() {}
+
+  // Called when a message is received from MessageService (Chrome).
+  virtual void OnMessage(const std::string& message) = 0;
+
+  // Sets the client to start receiving messages from the native host.
+  virtual void Start(Client* client) = 0;
+
+  // Returns the task runner that the host runs on. The Client should only
+  // invoke OnMessage() on this task runner.
+  virtual scoped_refptr<base::SingleThreadTaskRunner> task_runner() const = 0;
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_API_MESSAGING_NATIVE_MESSAGE_HOST_H_