Revert to repair UI test bustage

base/message_pump_win.cc

 // Copyright (c) 2006-2008 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_pump_win.h"
 
 #include <math.h>
 
 #include "base/histogram.h"
 #include "base/win_util.h"
@@ skipping 362 matching lines @@
   // then resets the have_work_ flag (allowing a replacement kMsgHaveWork to
   // possibly be posted), and finally dispatches that peeked replacement.  Note
   // that the re-post of kMsgHaveWork may be asynchronous to this thread!!
 
   MSG msg;
   bool have_message = (0 != PeekMessage(&msg, NULL, 0, 0, PM_REMOVE));
   DCHECK(!have_message || kMsgHaveWork != msg.message ||
          msg.hwnd != message_hwnd_);
 
   // Since we discarded a kMsgHaveWork message, we must update the flag.
-  int old_have_work = InterlockedExchange(&have_work_, 0);
-  DCHECK(old_have_work);
+  InterlockedExchange(&have_work_, 0);
 
-  // We don't need a special time slice if we didn't have_message to process. 
-  if (!have_message)
-    return false;
+  // TODO(darin,jar): There is risk of being lost in a sub-pump within the call
+  // to ProcessMessageHelper, which could result in no longer getting a
+  // kMsgHaveWork message until the next out-of-band call to ScheduleWork.
 
-  // Guarantee we'll get another time slice in the case where we go into native
-  // windows code.   This ScheduleWork() may hurt performance a tiny bit when
-  // tasks appear very infrequently, but when the event queue is busy, the
-  // kMsgHaveWork events get (percentage wise) rarer and rarer.
-  ScheduleWork();
-  return ProcessMessageHelper(msg);
+  return have_message && ProcessMessageHelper(msg);
 }
 
 //-----------------------------------------------------------------------------
 // MessagePumpForIO public:
 
 MessagePumpForIO::MessagePumpForIO() {
   port_.Set(CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, NULL, 1));
   DCHECK(port_.IsValid());
 }
 
@@ skipping 141 matching lines @@
     if (!filter || it->handler == filter) {
       *item = *it;
       completed_io_.erase(it);
       return true;
     }
   }
   return false;
 }
 
 }  // namespace base