Revert of Stop shutting down the message loop when the renderer stops

content/renderer/render_thread_impl.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/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <utility>
@@ skipping 950 matching lines @@
 
   // Shut down the message loop (if provided when the RenderThreadImpl was
   // constructed) and the renderer scheduler before shutting down Blink. This
   // prevents a scenario where a pending task in the message loop accesses Blink
   // objects after Blink shuts down.
   renderer_scheduler_->SetRAILModeObserver(nullptr);
   renderer_scheduler_->Shutdown();
 
   ChildThreadImpl::ShutdownDiscardableSharedMemoryManager();
 
+  if (main_message_loop_)
+    base::RunLoop().RunUntilIdle();
+
+  main_message_loop_.reset();
+
   lazy_tls.Pointer()->Set(nullptr);
 }
 
 bool RenderThreadImpl::Send(IPC::Message* msg) {
   // There are cases where we want to pump asynchronous messages while waiting
   // synchronously for the replies to the message to be sent here. However, this
   // may create an opportunity for re-entrancy into WebKit and other subsystems,
   // so we need to take care to disable callbacks, timers, and pending network
   // loads that could trigger such callbacks.
   bool pumping_events = false;
@@ skipping 1224 matching lines @@
       v8_memory_pressure_level == v8::MemoryPressureLevel::kCritical)
     v8_memory_pressure_level = v8::MemoryPressureLevel::kModerate;
 
   blink::mainThreadIsolate()->MemoryPressureNotification(
       v8_memory_pressure_level);
   blink::MemoryPressureNotificationToWorkerThreadIsolates(
       v8_memory_pressure_level);
 }
 
 }  // namespace content