[Windows] Fix for Browser IO MessageLoop spinning the CPU.

base/message_loop/message_loop.cc

 // Copyright 2013 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_loop.h"
 
 #include <algorithm>
+#include <limits>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_pump_default.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/run_loop.h"
@@ skipping 18 matching lines @@
 
 namespace base {
 
 namespace {
 
 // A lazily created thread local storage for quick access to a thread's message
 // loop, if one exists.  This should be safe and free of static constructors.
 LazyInstance<base::ThreadLocalPointer<MessageLoop> >::Leaky lazy_tls_ptr =
     LAZY_INSTANCE_INITIALIZER;
 
+// Delays larger than this many microseconds are likely bogus, and a warning
+// should be emitted in debug builds to warn developers.
+// http://crbug.com/450045
+const int kTaskDelayWarningThresholdInMicroseconds =
+    std::numeric_limits<int>::max() / 2;
+
 // Logical events for Histogram profiling. Run with -message-loop-histogrammer
 // to get an accounting of messages and actions taken on each thread.
 const int kTaskRunEvent = 0x1;
 #if !defined(OS_NACL)
 const int kTimerEvent = 0x2;
 
 // Provide range of message IDs for use in histogramming and debug display.
 const int kLeastNonZeroMessageId = 1;
 const int kMaxMessageId = 1099;
 const int kNumberOfDistinctMessagesDisplayed = 1100;
@@ skipping 212 matching lines @@
     const Closure& task) {
   DCHECK(!task.is_null()) << from_here.ToString();
   incoming_task_queue_->AddToIncomingQueue(from_here, task, TimeDelta(), true);
 }
 
 void MessageLoop::PostDelayedTask(
     const tracked_objects::Location& from_here,
     const Closure& task,
     TimeDelta delay) {
   DCHECK(!task.is_null()) << from_here.ToString();
+  DLOG_IF(WARNING,
+          delay.InMicroseconds() > kTaskDelayWarningThresholdInMicroseconds)
+      << "Requesting super-long task delay period of " << delay.InMicroseconds()
+      << " usec from " << from_here.ToString();
   incoming_task_queue_->AddToIncomingQueue(from_here, task, delay, true);
 }
 
 void MessageLoop::PostNonNestableTask(
     const tracked_objects::Location& from_here,
     const Closure& task) {
   DCHECK(!task.is_null()) << from_here.ToString();
   incoming_task_queue_->AddToIncomingQueue(from_here, task, TimeDelta(), false);
 }
 
 void MessageLoop::PostNonNestableDelayedTask(
     const tracked_objects::Location& from_here,
     const Closure& task,
     TimeDelta delay) {
   DCHECK(!task.is_null()) << from_here.ToString();
+  DLOG_IF(WARNING,
+          delay.InMicroseconds() > kTaskDelayWarningThresholdInMicroseconds)
+      << "Requesting super-long task delay period of " << delay.InMicroseconds()
+      << " usec from " << from_here.ToString();
   incoming_task_queue_->AddToIncomingQueue(from_here, task, delay, false);

[darin (slow to review), 2015/01/27 07:52:39]

would it be better to move this DLOG_IF to the implementation of
AddToIncomingQueue instead? that way it can be done in one place instead of two?

 }
 
 void MessageLoop::Run() {
   RunLoop run_loop;
   run_loop.Run();
 }
 
 void MessageLoop::RunUntilIdle() {
   RunLoop run_loop;
   run_loop.RunUntilIdle();
@@ skipping 395 matching lines @@
       persistent,
       mode,
       controller,
       delegate);
 }
 #endif
 
 #endif  // !defined(OS_NACL_SFI)
 
 }  // namespace base