Update from https://crrev.com/312398

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"
@@ skipping 144 matching lines @@
   UMA_HISTOGRAM_ENUMERATION("Chrome.MessageLoopProblem", SET_TIMER_ERROR,
                             MESSAGE_LOOP_PROBLEM_MAX);
 }
 
 //-----------------------------------------------------------------------------
 // MessagePumpForUI private:
 
 // static
 LRESULT CALLBACK MessagePumpForUI::WndProcThunk(
     HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
+  // TODO(vadimt): Remove ScopedTracker below once crbug.com/440919 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "440919 MessagePumpForUI::WndProcThunk"));
+
   switch (message) {
     case kMsgHaveWork:
       reinterpret_cast<MessagePumpForUI*>(wparam)->HandleWorkMessage();
       break;
     case WM_TIMER:
       reinterpret_cast<MessagePumpForUI*>(wparam)->HandleTimerMessage();
       break;
   }
   return DefWindowProc(hwnd, message, wparam, lparam);
 }
@@ skipping 473 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