Allow synchronous messages to be sent from threads other than the main thread...

chrome/common/child_thread.h

 // 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_COMMON_CHILD_THREAD_H_
 #define CHROME_COMMON_CHILD_THREAD_H_
 
 #include "base/basictypes.h"
 #include "base/scoped_ptr.h"
 #include "chrome/common/message_router.h"
 #include "chrome/common/resource_dispatcher.h"
 #include "ipc/ipc_sync_channel.h"
 #include "ipc/ipc_message.h"
 
 class NotificationService;
 class SocketStreamDispatcher;
 
+namespace IPC {
+class SyncMessageFilter;
+}
+
 // The main thread of a child process derives from this class.
 class ChildThread : public IPC::Channel::Listener,
                     public IPC::Message::Sender {
  public:
   // Creates the thread.
   ChildThread();
   // Used for single-process mode.
   explicit ChildThread(const std::string& channel_name);
   virtual ~ChildThread();
 
@@ skipping 14 matching lines @@
       int host_render_view_id);
 
   ResourceDispatcher* resource_dispatcher() {
     return resource_dispatcher_.get();
   }
 
   SocketStreamDispatcher* socket_stream_dispatcher() {
     return socket_stream_dispatcher_.get();
   }
 
+  // Safe to call on any thread, as long as it's guaranteed that the thread's
+  // lifetime is less than the main thread.
+  IPC::SyncMessageFilter* sync_message_filter() { return sync_message_filter_; }
+
   MessageLoop* message_loop() { return message_loop_; }
 
   // Returns the one child thread.
   static ChildThread* current();
 
  protected:
   friend class ChildProcess;
 
   // Called when the process refcount is 0.
   void OnProcessFinalRelease();
@@ skipping 15 matching lines @@
  private:
   void Init();
 
   // IPC::Channel::Listener implementation:
   virtual void OnMessageReceived(const IPC::Message& msg);
   virtual void OnChannelError();
 
   std::string channel_name_;
   scoped_ptr<IPC::SyncChannel> channel_;
 
+  // Allows threads other than the main thread to send sync messages.
+  scoped_refptr<IPC::SyncMessageFilter> sync_message_filter_;
+
   // Implements message routing functionality to the consumers of ChildThread.
   MessageRouter router_;
 
   // Handles resource loads for this process.
   scoped_ptr<ResourceDispatcher> resource_dispatcher_;
 
   // Handles SocketStream for this process.
   scoped_ptr<SocketStreamDispatcher> socket_stream_dispatcher_;
 
   // If true, checks with the browser process before shutdown.  This avoids race
   // conditions if the process refcount is 0 but there's an IPC message inflight
   // that would addref it.
   bool check_with_browser_before_shutdown_;
 
   // The OnChannelError() callback was invoked - the channel is dead, don't
   // attempt to communicate.
   bool on_channel_error_called_;
 
   MessageLoop* message_loop_;
 
   scoped_ptr<NotificationService> notification_service_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildThread);
 };
 
 #endif  // CHROME_COMMON_CHILD_THREAD_H_