Initial rev at a message passing API for extensions. So far, only passing

messages to the extension process is supported.
Review URL: http://codereview.chromium.org/48090

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@12319 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 73 insertions, 0 deletions

diff --git a/chrome/browser/extensions/extension_message_service.h b/chrome/browser/extensions/extension_message_service.h
new file mode 100755
index 0000000..eef1676
--- /dev/null
+++ b/chrome/browser/extensions/extension_message_service.h
@@ -0,0 +1,73 @@
+// Copyright (c) 2009 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 CHROME_BROWSER_EXTENSIONS_EXTENSION_MESSAGE_SERVICE_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_MESSAGE_SERVICE_H_
+
+#include <map>
+#include <string>
+
+class ExtensionView;
+class ResourceMessageFilter;
+
+// This class manages message passing to and from extension processes.  It
+// maintains a list of available extensions, as well as a set of open channels.
+// It should only be accessed on the IO thread, with the exception of
+// RegisterExtensionView().
+//
+// Terminology:
+// channel: connection between two ports (one of which belongs to an extension)
+// port: an IPC::Message::Sender interface through which we communicate to a
+//   process.  We use MessageFilters for this since that allows us to send our
+//   messages on the IO thread.
+class ExtensionMessageService {
+ public:
+  static ExtensionMessageService* GetInstance();
+
+  ExtensionMessageService();
+
+  // Registers an extension so that it can be referenced by its ID.  This method
+  // should only be used by the UI thread.
+  void RegisterExtensionView(ExtensionView* view);
+
+  // Given an extension's ID, opens a channel between the given renderer "port"
+  // and that extension.  Returns a channel ID to be used for posting messages
+  // between the processes, or -1 if the extension doesn't exist.
+  int OpenChannelToExtension(const std::string& extension_id,
+                             ResourceMessageFilter* renderer_port);
+
+  // Sends a message to the extension via the given channel.
+  void PostMessage(int channel_id, const std::string& message);
+
+  // Called to let us know that a renderer is going away.
+  void RendererShutdown(ResourceMessageFilter* renderer_port);
+ private:
+  class ExtensionFilter;
+  friend class ExtensionFilter;
+
+  // Called when our ExtensionFilter is ready/going away.
+  void OnExtensionRegistered(ExtensionFilter* extension);
+  void OnExtensionUnregistered(ExtensionFilter* extension);
+
+  // A map of extension ID to the extension port to communicate through.
+  // TODO(mpcomplete): Handle the case where there's multiple ExtensionViews
+  // in a given extension.
+  typedef std::map<std::string, ExtensionFilter*> ExtensionMap;
+  ExtensionMap extensions_;
+
+  // The connection between the renderer and extension.
+  struct MessageChannel {
+    ExtensionFilter* extension_port;
+    ResourceMessageFilter* renderer_port;
+  };
+
+  // A map of channel ID to its channel object.
+  typedef std::map<int, MessageChannel> MessageChannelMap;
+  MessageChannelMap channels_;
+
+  // For generating unique channel IDs.
+  int next_channel_id_;
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_MESSAGE_SERVICE_H_