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

base/message_loop/message_loop.cc

Index: base/message_loop/message_loop.cc
diff --git a/base/message_loop/message_loop.cc b/base/message_loop/message_loop.cc
index 818073367bdf2698a233a9aa46a79b878d3fbe7b..67ddbfa6c8c73a11d6188481d4f362c02207390b 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -5,6 +5,7 @@
 #include "base/message_loop/message_loop.h"
 
 #include <algorithm>
+#include <limits>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ -43,6 +44,12 @@ namespace {
 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;
@@ -275,6 +282,10 @@ void MessageLoop::PostDelayedTask(
     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);
 }
 
@@ -290,6 +301,10 @@ void MessageLoop::PostNonNestableDelayedTask(
     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?

 }