[Extensions] Begin making Extension port initialization asynchronous

extensions/renderer/extension_port.h

+// Copyright 2016 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_RENDERER_EXTENSION_PORT_H_
+#define EXTENSIONS_RENDERER_EXTENSION_PORT_H_
+
+#include <memory>
+#include <vector>
+
+#include "base/macros.h"
+
+namespace content {
+class RenderFrame;
+}
+
+namespace extensions {
+
+struct Message;
+class ScriptContext;
+
+// A class representing information about a specific extension message port that
+// handles sending related IPCs to the browser. Since global port IDs are
+// assigned asynchronously, this object caches pending messages.
+class ExtensionPort {
+ public:
+  ExtensionPort(ScriptContext* script_context, int local_id);
+  ~ExtensionPort();
+
+  // Sets the global id of the port (that is, the id used in the browser
+  // process to send/receive messages). Any pending messages will be sent.
+  void SetGlobalId(int id);
+
+  // Posts a new message to the port. If the port is not initialized, the
+  // message will be queued until it is.
+  void PostExtensionMessage(std::unique_ptr<Message> message);
+
+  // Closes the port. If there are pending messages, they will still be sent
+  // assuming initialization completes (after which, the port will close).
+  void Close(bool close_channel);
+
+  int local_id() const { return local_id_; }
+  int global_id() const { return global_id_; }
+  bool initialized() const { return global_id_ != -1; }
+
+ private:
+  // Helper function to send the post message IPC.
+  void PostMessageImpl(content::RenderFrame* render_frame,
+                       const Message& message);
+
+  // Sends the message to the browser that this port has been disconnected.
+  void SendDisconnected(content::RenderFrame* render_frame);
+
+  // The associated ScriptContext for this port. Since these objects are owned
+  // by a NativeHandler, this should always be valid.
+  ScriptContext* script_context_ = nullptr;
+
+  // The local id of the port (used within JS bindings).
+  int local_id_ = -1;
+
+  // The global id of the port (used by the browser process).
+  int global_id_ = -1;
+
+  // The queue of any pending messages to be sent once the port is initialized.
+  std::vector<std::unique_ptr<Message>> pending_messages_;
+
+  // Whether or not the port is disconnected.
+  bool is_disconnected_ = false;
+
+  // Whether to close the full message channel.
+  bool close_channel_ = false;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionPort);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_RENDERER_EXTENSION_PORT_H_