Update from https://crrev.com/316786

base/message_loop/message_loop.cc

 // Copyright 2013 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/message_loop/message_loop.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 134 matching lines @@
 #endif  // OS_WIN
       message_histogram_(NULL),
       run_loop_(NULL) {
   DCHECK(pump_.get());
   Init();
 }
 
 MessageLoop::~MessageLoop() {
   DCHECK_EQ(this, current());
 
+  // iOS just attaches to the loop, it doesn't Run it.
+  // TODO(stuartmorgan): Consider wiring up a Detach().
+#if !defined(OS_IOS)
   DCHECK(!run_loop_);
+#endif
+
 #if defined(OS_WIN)
   if (in_high_res_mode_)
     Time::ActivateHighResolutionTimer(false);
 #endif
   // Clean up any unprocessed tasks, but take care: deleting a task could
   // result in the addition of more tasks (e.g., via DeleteSoon).  We set a
   // limit on the number of times we will allow a deleted task to generate more
   // tasks.  Normally, we should only pass through this loop once or twice.  If
   // we end up hitting the loop limit, then it is probably due to one task that
   // is being stubborn.  Inspect the queues to see who is left.
@@ skipping 544 matching lines @@
       persistent,
       mode,
       controller,
       delegate);
 }
 #endif
 
 #endif  // !defined(OS_NACL_SFI)
 
 }  // namespace base