Web MIDI: introduce MidiManager::Shutdown to shutdown gracefully

content/browser/browser_main_loop.cc

 // Copyright (c) 2012 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 "content/browser/browser_main_loop.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/logging.h"
@@ skipping 672 matching lines @@
         chromeos::switches::GetMemoryPressureThresholds()));
   }
 #elif defined(OS_MACOSX) && !defined(OS_IOS)
   memory_pressure_monitor_.reset(new base::mac::MemoryPressureMonitor());
 #elif defined(OS_WIN)
   memory_pressure_monitor_.reset(CreateWinMemoryPressureMonitor(
       parsed_command_line_));
 #endif
 
 #if defined(ENABLE_PLUGINS)
-  // Prior to any processing happening on the io thread, we create the
-  // plugin service as it is predominantly used from the io thread,
+  // Prior to any processing happening on the IO thread, we create the
+  // plugin service as it is predominantly used from the IO thread,
   // but must be created on the main thread. The service ctor is
   // inexpensive and does not invoke the io_thread() accessor.
   {
     TRACE_EVENT0("startup", "BrowserMainLoop::CreateThreads:PluginService");
     PluginService::GetInstance()->Init();
   }
 #endif
 
 #if defined(OS_MACOSX)
   {
@@ skipping 236 matching lines @@
   // stopping the GPU thread. The GPU thread will close IPC channels to renderer
   // processes so this has to happen before stopping the IO thread.
   {
     TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:GPUProcessHostShim");
     GpuProcessHostUIShim::DestroyAll();
   }
   // Cancel pending requests and prevent new requests.
   if (resource_dispatcher_host_) {
     TRACE_EVENT0("shutdown",
                  "BrowserMainLoop::Subsystem:ResourceDispatcherHost");
-    resource_dispatcher_host_.get()->Shutdown();
+    resource_dispatcher_host_->Shutdown();
+  }
+  // Request shutdown to clean up allocated resources on the IO thread.
+  if (midi_manager_) {
+    TRACE_EVENT0("shutdown",
+                 "BrowserMainLoop::Subsystem:MidiManager");
+    midi_manager_->Shutdown();
   }
 
   memory_pressure_monitor_.reset();
 
 #if defined(OS_MACOSX)
   BrowserCompositorMac::DisableRecyclingForShutdown();
 #endif
 
 #if defined(USE_AURA) || defined(OS_MACOSX)
   {
@@ skipping 420 matching lines @@
   DCHECK(is_tracing_startup_for_duration_);
 
   is_tracing_startup_for_duration_ = false;
   TracingController::GetInstance()->DisableRecording(
       TracingController::CreateFileSink(
           startup_trace_file_,
           base::Bind(OnStoppedStartupTracing, startup_trace_file_)));
 }
 
 }  // namespace content