[Ozone-Drm] Do not try to take ref_ptr from destructor

ui/ozone/platform/drm/gpu/drm_device.cc

 // Copyright 2014 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 "ui/ozone/platform/drm/gpu/drm_device.h"
 
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <unistd.h>
 #include <xf86drm.h>
@@ skipping 96 matching lines @@
       : io_task_runner_(io_task_runner), paused_(true), fd_(fd) {}
 
   void SetPaused(bool paused) {
     if (paused_ == paused)
       return;
 
     paused_ = paused;
     base::WaitableEvent done(false, false);
     io_task_runner_->PostTask(
         FROM_HERE, base::Bind(&IOWatcher::SetPausedOnIO, this, &done));
+    done.Wait();
   }
 
   void Shutdown() {
     if (!paused_)
       io_task_runner_->PostTask(FROM_HERE,
                                 base::Bind(&IOWatcher::UnregisterOnIO, this));
   }
 
  private:
   friend class base::RefCountedThreadSafe<IOWatcher>;
 
-  ~IOWatcher() override { SetPaused(true); }
+  ~IOWatcher() override {}
 
   void RegisterOnIO() {
     DCHECK(base::MessageLoopForIO::IsCurrent());
     base::MessageLoopForIO::current()->WatchFileDescriptor(
         fd_, true, base::MessageLoopForIO::WATCH_READ, &controller_, this);
   }
 
   void UnregisterOnIO() {
     DCHECK(base::MessageLoopForIO::IsCurrent());
     controller_.StopWatchingFileDescriptor();
@@ skipping 304 matching lines @@
   DCHECK(file_.IsValid());
   return (drmSetMaster(file_.GetPlatformFile()) == 0);
 }
 
 bool DrmDevice::DropMaster() {
   DCHECK(file_.IsValid());
   return (drmDropMaster(file_.GetPlatformFile()) == 0);
 }
 
 }  // namespace ui