mac/linux: rework plugin channel file descriptor creation

chrome/plugin/plugin_thread.cc

Index: chrome/plugin/plugin_thread.cc
diff --git a/chrome/plugin/plugin_thread.cc b/chrome/plugin/plugin_thread.cc
index 2f9c2ec3a916f9e648eb6775efb814659c5fbf28..2701f5b543bf7ceddda9d823cadd3342f9684a4a 100644
--- a/chrome/plugin/plugin_thread.cc
+++ b/chrome/plugin/plugin_thread.cc
@@ -103,24 +103,23 @@ void PluginThread::CleanUp() {
 }
 
 void PluginThread::OnCreateChannel(
-#if defined(OS_POSIX)
-    base::FileDescriptor socket,
-#endif
     int process_id,
     bool off_the_record) {
-  int fd = -1;
-#if defined(OS_POSIX)
-  fd = socket.fd;
-#endif
-  std::string channel_name;
   scoped_refptr<PluginChannel> channel =
-      PluginChannel::GetPluginChannel(process_id, owner_loop(), fd);
+      PluginChannel::GetPluginChannel(process_id, owner_loop());
+  IPC::ChannelHandle channel_handle;
   if (channel.get()) {
-    channel_name = channel->channel_name();
+    channel_handle.name = channel->channel_name();
+#if defined(OS_POSIX)
+    // On POSIX, pass the renderer-side FD. Also mark it as auto-close so that
+    // it gets closed after it has been sent.
+    int renderer_fd = channel->DisownRendererFd();
+    channel_handle.socket = base::FileDescriptor(renderer_fd, true);
+#endif
     channel->set_off_the_record(off_the_record);
   }
 
-  Send(new PluginProcessHostMsg_ChannelCreated(channel_name));
+  Send(new PluginProcessHostMsg_ChannelCreated(channel_handle));
 }
 
 void PluginThread::OnPluginMessage(const std::vector<unsigned char> &data) {