Fix hung renderer timer code in RenderWidgetHost (task spam bug)

content/browser/renderer_host/render_widget_host.cc

Index: content/browser/renderer_host/render_widget_host.cc
diff --git a/content/browser/renderer_host/render_widget_host.cc b/content/browser/renderer_host/render_widget_host.cc
index 404ff86093ef97319b1da921c70cda7dfbc631d1..e1bb3f585c28aec9457f0b6da2c5ce061a77f0c2 100644
--- a/content/browser/renderer_host/render_widget_host.cc
+++ b/content/browser/renderer_host/render_widget_host.cc
@@ -506,19 +506,21 @@ void RenderWidgetHost::StartHangMonitorTimeout(TimeDelta delay) {
     return;
   }
 
+  // Set time_when_considered_hung_ if it's null.
+  Time requested_end_time = Time::Now() + delay;
+  if (time_when_considered_hung_.is_null())
+    time_when_considered_hung_ = requested_end_time;
+
   // If we already have a timer that will expire at or before the given delay,

[Charlie Reis, 2011/11/11 02:20:10]

Maybe we can update this comment to reflect what you said about GetCurrentDelay
(that it returns the timer's total duration, not the remaining time).  Something
like:
"If we already have a timer with the same or shorter duration, then we can wait
for it to finish."

This may of course finish before the time_when_considered_hung_, but
CheckRendererIsUnresponsive can handle that by starting a new timer for the
remainder, so we're fine.

[jbates, 2011/11/11 02:40:13]

Done.

-  // then we have nothing more to do now.  If we have set our end time to null
-  // by calling StopHangMonitorTimeout, though, we will need to restart the
-  // timer.
+  // then we have nothing more to do now.
   if (hung_renderer_timer_.IsRunning() &&
-      hung_renderer_timer_.GetCurrentDelay() <= delay &&
-      !time_when_considered_hung_.is_null()) {
+      hung_renderer_timer_.GetCurrentDelay() <= delay) {
     return;
   }
 
   // Either the timer is not yet running, or we need to adjust the timer to
   // fire sooner.
-  time_when_considered_hung_ = Time::Now() + delay;
+  time_when_considered_hung_ = requested_end_time;
   hung_renderer_timer_.Stop();
   hung_renderer_timer_.Start(FROM_HERE, delay, this,
       &RenderWidgetHost::CheckRendererIsUnresponsive);