Fix shutdown assert with the new Mojo EDK.

mojo/edk/system/routed_raw_channel.cc

Index: mojo/edk/system/routed_raw_channel.cc
diff --git a/mojo/edk/system/routed_raw_channel.cc b/mojo/edk/system/routed_raw_channel.cc
index 825fc2fac30d36b2982b4a497fed78c98d07d893..5bb89a582e898801aa3625b486d5cd880fd2d767 100644
--- a/mojo/edk/system/routed_raw_channel.cc
+++ b/mojo/edk/system/routed_raw_channel.cc
@@ -131,9 +131,14 @@ void RoutedRawChannel::OnReadMessage(
 
 void RoutedRawChannel::OnError(Error error) {
   DCHECK(internal::g_io_thread_task_runner->RunsTasksOnCurrentThread());
+
+  // This needs to match non-multiplexed MessagePipeDispatcher's destruction of
+  // the channel only when read errors occur.
+  if (error != ERROR_WRITE) {
+    channel_->Shutdown();
+    channel_ = nullptr;
+  }
 
-  channel_->Shutdown();
-  channel_ = nullptr;
   if (routes_.empty()) {
     delete this;
     return;