Pending tasks in a message loop should be deleted before shutting down Blink

content/renderer/renderer_main.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 "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/debug/debugger.h"
 #include "base/debug/stack_trace.h"
 #include "base/debug/trace_event.h"
 #include "base/i18n/rtl.h"
@@ skipping 212 matching lines @@
 
     if (run_loop) {
 #if defined(OS_MACOSX)
       if (pool)
         pool->Recycle();
 #endif
       TRACE_EVENT_BEGIN_ETW("RendererMain.START_MSG_LOOP", 0, 0);
       base::MessageLoop::current()->Run();
       TRACE_EVENT_END_ETW("RendererMain.START_MSG_LOOP", 0, 0);
     }
+
+    // Since the destructors of the pending tasks can touch Blink objects,
+    // we need to make sure that all pending tasks are deleted before
+    // shutting down Blink (Blink is shut down in the RenderProcessImpl's
+    // destructor).
+    main_message_loop.DeletePendingTasks();

[jamesr, 2014/09/22 14:38:04]

since you're deleting *all* pending tasks and not just Blink ones then you
definitely do not care about anything else running, so not lgtm.  You should
simply shut down the loop before shutting down blink

[haraken, 2014/09/22 15:54:18]

I'm not familiar with a message loop, but what's a common way to completely shut
down the main_message_loop here?

At first I tried something like:

scoped_ptr<base::MessageLoop> main_message_loop(new base::MessageLoop());  //
line 155
{
  ...;
  main_message_loop.reset();  // line 238
}

but it crashed chrome :-/

   }
   platform.PlatformUninitialize();
   TRACE_EVENT_END_ETW("RendererMain", 0, "");
   return 0;
 }
 
 }  // namespace content