Fix nullptr deref in remote interface acquisition

ipc/ipc_message_pipe_reader.cc

Index: ipc/ipc_message_pipe_reader.cc
diff --git a/ipc/ipc_message_pipe_reader.cc b/ipc/ipc_message_pipe_reader.cc
index 8e1b35565bfec09fbabb25835542fbd3e403f627..32c9f9e0c924e5e5be87c450314595bce5ed3a47 100644
--- a/ipc/ipc_message_pipe_reader.cc
+++ b/ipc/ipc_message_pipe_reader.cc
@@ -116,6 +116,8 @@ bool MessagePipeReader::Send(std::unique_ptr<Message> message) {
 void MessagePipeReader::GetRemoteInterface(
     const std::string& name,
     mojo::ScopedInterfaceEndpointHandle handle) {
+  if (!sender_.is_bound())
+    return;
   mojom::GenericInterfaceAssociatedRequest request;
   request.Bind(std::move(handle));
   sender_->GetAssociatedInterface(name, std::move(request));