Bug 613442, part 3: Add AsyncChannel::Echo() to allow sending a message back to the originating endpoint. r=bent

ipc/glue/AsyncChannel.cpp

@@ -247,6 +247,33 @@ AsyncChannel::Send(Message* msg)
     return true;
 }
 
+bool
+AsyncChannel::Echo(Message* msg)
+{
+    AssertWorkerThread();
+    mMonitor.AssertNotCurrentThreadOwns();
+    NS_ABORT_IF_FALSE(MSG_ROUTING_NONE != msg->routing_id(), "need a route");
+
+    {
+        MonitorAutoLock lock(mMonitor);
+
+        if (!Connected()) {
+            ReportConnectionError("AsyncChannel");
+            return false;
+        }
+
+        // NB: Go through this OnMessageReceived indirection so that
+        // echoing this message does the right thing for SyncChannel
+        // and RPCChannel too
+        mIOLoop->PostTask(
+            FROM_HERE,
+            NewRunnableMethod(this, &AsyncChannel::OnEchoMessage, msg));
+        // OnEchoMessage takes ownership of |msg|
+    }
+
+    return true;
+}
+
 void
 AsyncChannel::OnDispatchMessage(const Message& msg)
 {
@@ -470,6 +497,14 @@ AsyncChannel::OnMessageReceived(const Message& msg)
             NewRunnableMethod(this, &AsyncChannel::OnDispatchMessage, msg));
 }
 
+void
+AsyncChannel::OnEchoMessage(Message* msg)
+{
+    AssertIOThread();
+    OnMessageReceived(*msg);
+    delete msg;
+}
+
 void
 AsyncChannel::OnChannelOpened()
 {

ipc/glue/AsyncChannel.h

@@ -117,6 +117,10 @@ public:
     // Asynchronously send a message to the other side of the channel
     virtual bool Send(Message* msg);
 
+    // Asynchronously deliver a message back to this side of the
+    // channel
+    virtual bool Echo(Message* msg);
+
     // Send OnChannelConnected notification to listeners.
     void DispatchOnChannelConnected(int32 peer_pid);
 
@@ -177,6 +181,7 @@ protected:
     void OnChannelOpened();
     void OnCloseChannel();
     void PostErrorNotifyTask();
+    void OnEchoMessage(Message* msg);
 
     // Return true if |msg| is a special message targeted at the IO
     // thread, in which case it shouldn't be delivered to the worker.