Support mojo connections between unrelated peer processes.

mojo/edk/system/node_channel.cc

Index: mojo/edk/system/node_channel.cc
diff --git a/mojo/edk/system/node_channel.cc b/mojo/edk/system/node_channel.cc
index 114e2863560b88c443049dbb1de8764c3e6858ef..da9e0dbf25c3bcd53413b119e566e11e28365d0c 100644
--- a/mojo/edk/system/node_channel.cc
+++ b/mojo/edk/system/node_channel.cc
@@ -47,6 +47,7 @@ enum class MessageType : uint32_t {
 #if defined(OS_WIN) || (defined(OS_MACOSX) && !defined(OS_IOS))
   PORTS_MESSAGE_FROM_RELAY,
 #endif
+  ACCEPT_PEER,
 };
 
 struct Header {
@@ -67,6 +68,12 @@ struct AcceptParentData {
   ports::NodeName child_name;
 };
 
+struct AcceptPeerData {
+  ports::NodeName token;
+  ports::NodeName peer_name;
+  ports::PortName port_name;
+};
+
 // This message may include a process handle on plaforms that require it.
 struct AddBrokerClientData {
   ports::NodeName client_name;
@@ -282,6 +289,18 @@ void NodeChannel::AcceptParent(const ports::NodeName& token,
   WriteChannelMessage(std::move(message));
 }
 
+void NodeChannel::AcceptPeer(const ports::NodeName& sender_name,
+                             const ports::NodeName& token,
+                             const ports::PortName& port_name) {
+  AcceptPeerData* data;
+  Channel::MessagePtr message =
+      CreateMessage(MessageType::ACCEPT_PEER, sizeof(AcceptPeerData), 0, &data);
+  data->token = token;
+  data->peer_name = sender_name;
+  data->port_name = port_name;
+  WriteChannelMessage(std::move(message));
+}
+
 void NodeChannel::AddBrokerClient(const ports::NodeName& client_name,
                                   base::ProcessHandle process_handle) {
   AddBrokerClientData* data;
@@ -728,6 +747,16 @@ void NodeChannel::OnChannelMessage(const void* payload,
 
 #endif  // defined(OS_WIN) || (defined(OS_MACOSX) && !defined(OS_IOS))
 
+    case MessageType::ACCEPT_PEER: {
+      const AcceptPeerData* data;
+      if (GetMessagePayload(payload, payload_size, &data)) {
+        delegate_->OnAcceptPeer(remote_node_name_, data->token, data->peer_name,
+                                data->port_name);
+        return;
+      }
+      break;
+    }
+
     default:
       break;
   }