Emit a console warning when blocking event listener is delayed for too long

third_party/WebKit/Source/core/events/EventTarget.cpp

Index: third_party/WebKit/Source/core/events/EventTarget.cpp
diff --git a/third_party/WebKit/Source/core/events/EventTarget.cpp b/third_party/WebKit/Source/core/events/EventTarget.cpp
index 230c6756ff1dd0844ccd0969d4815389b1012a73..9807704622f5da2b445edc745d8a97429d1ed1f7 100644
--- a/third_party/WebKit/Source/core/events/EventTarget.cpp
+++ b/third_party/WebKit/Source/core/events/EventTarget.cpp
@@ -416,11 +416,19 @@ void EventTarget::fireEventListeners(Event* event, EventTargetData* d, EventList
             UseCounter::count(executingWindow->document(), UseCounter::TextInputFired);
     }
 
+    ExecutionContext* context = getExecutionContext();
+    if (!context)
+        return;
+
     size_t i = 0;
     size_t size = entry.size();
     if (!d->firingEventIterators)
         d->firingEventIterators = adoptPtr(new FiringEventIteratorVector);
     d->firingEventIterators->append(FiringEventIterator(event->type(), i, size));
+
+    bool shouldReportBlockedEvent = InspectorInstrumentation::shouldReportBlockedEvent(context, event);

[pfeldman, 2016/05/04 22:58:01]

Lets instead call EventTarget::logBlockedEventsToConsole();

+    double eventBlockedTime = shouldReportBlockedEvent ? WTF::monotonicallyIncreasingTime() - event->platformTimeStamp() : 0;
+
     while (i < size) {
         RegisteredEventListener& registeredListener = entry[i];
 
@@ -439,10 +447,6 @@ void EventTarget::fireEventListeners(Event* event, EventTargetData* d, EventList
         if (event->immediatePropagationStopped())
             break;
 
-        ExecutionContext* context = getExecutionContext();
-        if (!context)
-            break;
-
         event->setHandlingPassive(registeredListener.passive);
 
         InspectorInstrumentation::NativeBreakpoint nativeBreakpoint(context, this, event);
@@ -450,6 +454,10 @@ void EventTarget::fireEventListeners(Event* event, EventTargetData* d, EventList
         // To match Mozilla, the AT_TARGET phase fires both capturing and bubbling
         // event listeners, even though that violates some versions of the DOM spec.
         registeredListener.listener->handleEvent(context, event);
+
+        if (shouldReportBlockedEvent && !registeredListener.passive && !registeredListener.blockedEventWarningEmitted && !event->defaultPrevented())
+            InspectorInstrumentation::reportBlockedEvent(context, event, &registeredListener, eventBlockedTime);
+
         event->setHandlingPassive(false);
 
         RELEASE_ASSERT(i <= size);