Add UMA metric for tracking listeners for blocking touch before page finished loading

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 3870 matching lines @@
         const AtomicString& eventName(touchEventNameForTouchPointState(static_cast<PlatformTouchPoint::TouchState>(state)));
         for (const auto& eventTarget : changedTouches[state].m_targets) {
             EventTarget* touchEventTarget = eventTarget;
             TouchEvent* touchEvent = TouchEvent::create(
                 touches, touchesByTarget.get(touchEventTarget), changedTouches[state].m_touches.get(),
                 eventName, touchEventTarget->toNode()->document().domWindow(),
                 event.getModifiers(), event.cancelable(), event.causesScrollingIfUncanceled(), event.timestamp());
 
             DispatchEventResult domDispatchResult = touchEventTarget->dispatchEvent(touchEvent);
 
-            // Only report for top level documents with a single touch on
-            // touch-start or the first touch-move.
-            if (touchStartOrFirstTouchMove && touchInfos.size() == 1 && event.cancelable() && !m_frame->document()->ownerElement()) {
-                DEFINE_STATIC_LOCAL(EnumerationHistogram, rootDocumentListenerHistogram, ("Event.Touch.TargetAndDispatchResult", TouchTargetAndDispatchResultTypeMax));
-                rootDocumentListenerHistogram.count(toTouchTargetHistogramValue(eventTarget, domDispatchResult));
+            if (touchStartOrFirstTouchMove && touchInfos.size() == 1 && event.cancelable()) {
+                // Only report for top level documents with a single touch on
+                // touch-start or the first touch-move.
+                if (!m_frame->document()->ownerElement()) {
+                    DEFINE_STATIC_LOCAL(EnumerationHistogram, rootDocumentListenerHistogram, ("Event.Touch.TargetAndDispatchResult", TouchTargetAndDispatchResultTypeMax));
+                    rootDocumentListenerHistogram.count(toTouchTargetHistogramValue(eventTarget, domDispatchResult));
+                }
+
+                // Only count the canceled touch starts and first touch moves listener before page finishes loading.
+                if (!m_frame->document()->isLoadCompleted()) {
+                    DEFINE_STATIC_LOCAL(EnumerationHistogram, pageloadListenerHistogram, ("Event.Touch.TouchBlockingOnPageload", 2));

[dtapuska, 2016/04/22 17:34:14]

I'd prefer if these were called out as enums; as opposed to a magical 0, 1,
boolean.

[tdresser, 2016/04/22 17:34:52]

Let's have two histograms, once for before pageload, and once for after
pageload.

Event.Touch.TouchesCancelledBeforePageLoad
Event.Touch.TouchesCancelledAfterPageLoad

or something like that?

We should probably only be looking at cancelable touch events, right? Or we
should break the histogram up into more buckets, similar to what Dave has done.

[tdresser, 2016/04/22 17:37:06]

Sorry, missed the condition above that checked that we're only looking at
cancelable events.

[dtapuska, 2016/04/22 17:39:10]

How do we want to report this for iframes?

[tdresser, 2016/04/22 17:51:13]

I think we should only care about the top frame's document. It won't be
considered loaded until all subframes are loaded.

[dtapuska, 2016/04/22 18:02:35]

Right so the !m_frame->document()->ownerElement() should move back up to the top
if conditional.

+                    pageloadListenerHistogram.count((domDispatchResult != DispatchEventResult::NotCanceled) ? 1 : 0);
+                }
             }
             eventResult = mergeEventResult(eventResult, toWebInputEventResult(domDispatchResult));
         }
     }
 
     return eventResult;
 }
 
 WebInputEventResult EventHandler::handleTouchEvent(const PlatformTouchEvent& event)
 {
@@ skipping 264 matching lines @@
 PlatformEvent::Modifiers EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return static_cast<PlatformEvent::Modifiers>(PlatformEvent::CtrlKey | PlatformEvent::AltKey);
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace blink