Eliminate outgoing InterfaceProvider

mash/app_driver/app_driver.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mash/app_driver/app_driver.h"
 
 #include <stdint.h>
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 79 matching lines @@
 void AppDriver::OnStart(const shell::Identity& identity) {
   AddAccelerators();
 }
 
 bool AppDriver::OnConnect(shell::Connection* connection) {
   return true;
 }
 
 bool AppDriver::OnStop() {
   // Prevent the code in AddAccelerators() from keeping this app alive.
-  binding_.set_connection_error_handler(base::Bind(&DoNothing));
+  if (binding_.is_bound())
+    binding_.set_connection_error_handler(base::Bind(&DoNothing));
   return true;
 }
 
 void AppDriver::OnAccelerator(uint32_t id, std::unique_ptr<ui::Event> event) {
   struct LaunchOptions {
     uint32_t option;
     const char* app;
     LaunchMode mode;
   };
 
@@ skipping 20 matching lines @@
 
 void AppDriver::AddAccelerators() {
   connector()->ConnectToInterface("mojo:catalog", &catalog_);
   catalog_->GetEntriesProvidingClass(
       "mus:window_manager", base::Bind(&AppDriver::OnAvailableCatalogEntries,
                                        weak_factory_.GetWeakPtr()));
 }
 
 }  // namespace app_driver
 }  // namespace mash