Update from https://crrev.com/308331

base/message_loop/message_pump_win.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/message_loop/message_pump_win.h"
 
 #include <math.h>
 
 #include "base/debug/trace_event.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/process/memory.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/strings/stringprintf.h"
 #include "base/win/wrapped_window_proc.h"
 
 namespace base {
 
 namespace {
 
 enum MessageLoopProblems {
   MESSAGE_POST_ERROR,
   COMPLETION_POST_ERROR,
@@ skipping 289 matching lines @@
     return;
 
   state_->delegate->DoDelayedWork(&delayed_work_time_);
   if (!delayed_work_time_.is_null()) {
     // A bit gratuitous to set delayed_work_time_ again, but oh well.
     ScheduleDelayedWork(delayed_work_time_);
   }
 }
 
 bool MessagePumpForUI::ProcessNextWindowsMessage() {
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/440919 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "440919 <<MessagePumpForUI::ProcessNextWindowsMessage>>"));
+
   // If there are sent messages in the queue then PeekMessage internally
   // dispatches the message and returns false. We return true in this
   // case to ensure that the message loop peeks again instead of calling
   // MsgWaitForMultipleObjectsEx again.
   bool sent_messages_in_queue = false;
   DWORD queue_status = GetQueueStatus(QS_SENDMESSAGE);
   if (HIWORD(queue_status) & QS_SENDMESSAGE)
     sent_messages_in_queue = true;
 
   MSG msg;
@@ skipping 295 matching lines @@
 
 // static
 MessagePumpForIO::IOHandler* MessagePumpForIO::KeyToHandler(
     ULONG_PTR key,
     bool* has_valid_io_context) {
   *has_valid_io_context = ((key & 1) == 0);
   return reinterpret_cast<IOHandler*>(key & ~static_cast<ULONG_PTR>(1));
 }
 
 }  // namespace base