Bookkeep the pointer event listeners added to page

third_party/WebKit/Source/core/input/PointerEventManager.cpp

Index: third_party/WebKit/Source/core/input/PointerEventManager.cpp
diff --git a/third_party/WebKit/Source/core/input/PointerEventManager.cpp b/third_party/WebKit/Source/core/input/PointerEventManager.cpp
index 798a336662dfbd9f8346265269e2788c16a9cc0a..03e51099dae60ceb9e3bb7937723e96928b39cba 100644
--- a/third_party/WebKit/Source/core/input/PointerEventManager.cpp
+++ b/third_party/WebKit/Source/core/input/PointerEventManager.cpp
@@ -8,6 +8,7 @@
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/shadow/FlatTreeTraversal.h"
 #include "core/events/MouseEvent.h"
+#include "core/frame/EventHandlerRegistry.h"
 #include "core/frame/LocalFrameView.h"
 #include "core/frame/UseCounter.h"
 #include "core/html/HTMLCanvasElement.h"
@@ -28,6 +29,9 @@ namespace {
 size_t ToPointerTypeIndex(WebPointerProperties::PointerType t) {
   return static_cast<size_t>(t);
 }
+bool HasPointerEventListener(const EventHandlerRegistry& registry) {
+  return registry.HasEventHandlers(EventHandlerRegistry::kPointerEvent);
+}
 
 Vector<std::pair<WebTouchPoint, TimeTicks>> GetCoalescedPoints(
     const Vector<WebTouchEvent>& coalesced_events,
@@ -159,8 +163,11 @@ WebInputEventResult PointerEventManager::DispatchPointerEvent(
     }
   }
 
-  if (!RuntimeEnabledFeatures::pointerEventEnabled())
+  if (!frame_ || !frame_->GetPage() ||
+      !HasPointerEventListener(frame_->GetPage()->GetEventHandlerRegistry()) ||
+      !RuntimeEnabledFeatures::pointerEventEnabled())

[dtapuska, 2017/06/01 16:03:01]

We should probably log a bug to remove
RuntimeEnabledFeatures::pointerEventEnabled no? Since it has long shipped?

[Navid Zolghadr, 2017/06/01 16:10:41]

We have a bug for this:
crbug.com/687976

[eirage, 2017/06/01 19:59:24]

Acknowledged.

     return WebInputEventResult::kNotHandled;
+
   if (!check_for_listener || target->HasEventListeners(event_type)) {
     UseCounter::Count(frame_, UseCounter::kPointerEventDispatch);
     if (event_type == EventTypeNames::pointerdown)