Use the location where FileDescriptorWatcher is created to track the libevent handlers

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 334 matching lines @@
   uint64_t next_id_;
 
   std::vector<PageFlip> callbacks_;
 
   DISALLOW_COPY_AND_ASSIGN(PageFlipManager);
 };
 
 class DrmDevice::IOWatcher : public base::MessagePumpLibevent::Watcher {
  public:
   IOWatcher(int fd, DrmDevice::PageFlipManager* page_flip_manager)
-      : page_flip_manager_(page_flip_manager), fd_(fd) {
+      : page_flip_manager_(page_flip_manager), controller_(FROM_HERE), fd_(fd) {
     Register();
   }
 
   ~IOWatcher() override { Unregister(); }
 
  private:
   void Register() {
     DCHECK(base::MessageLoopForIO::IsCurrent());
     base::MessageLoopForIO::current()->WatchFileDescriptor(
         fd_, true, base::MessageLoopForIO::WATCH_READ, &controller_, this);
@@ skipping 452 matching lines @@
               reinterpret_cast<unsigned char*>(ctm_blob_data.get()),
               sizeof(DrmColorCtm)))
         return false;
     }
   }
 
   return true;
 }
 
 }  // namespace ui