Revert of Quit the message loop by default in ShellConnectionLost when ApplicationRunner is used

mojo/services/tracing/tracing_app.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 "mojo/services/tracing/tracing_app.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 24 matching lines @@
   if (tracing_active_) {
     TraceRecorderPtr recorder_ptr;
     recorder_impls_.push_back(
         new TraceRecorderImpl(GetProxy(&recorder_ptr), sink_.get()));
     provider_ptr->StartTracing(tracing_categories_, std::move(recorder_ptr));
   }
   provider_ptrs_.AddInterfacePtr(std::move(provider_ptr));
   return true;
 }
 
-bool TracingApp::ShellConnectionLost() {
-  // TODO(beng): This is only required because TracingApp isn't run by
-  // ApplicationRunner - instead it's launched automatically by the standalone
-  // shell. It shouldn't be.
+void TracingApp::ShellConnectionLost() {
   base::MessageLoop::current()->QuitWhenIdle();
-  return false;
 }
 
 void TracingApp::Create(mojo::Connection* connection,
                         mojo::InterfaceRequest<TraceCollector> request) {
   collector_binding_.Bind(std::move(request));
 }
 
 void TracingApp::Create(
     mojo::Connection* connection,
     mojo::InterfaceRequest<StartupPerformanceDataCollector> request) {
@@ skipping 116 matching lines @@
     const GetStartupPerformanceTimesCallback& callback) {
   callback.Run(startup_performance_times_.Clone());
 }
 
 void TracingApp::AllDataCollected() {
   recorder_impls_.clear();
   sink_.reset();
 }
 
 }  // namespace tracing