Remove the blocking touch handlers for the input[type=range] and add touch-action instead

third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 13 matching lines @@
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/html/shadow/SliderThumbElement.h"
 
+#include "core/dom/shadow/ShadowRoot.h"
 #include "core/events/Event.h"
 #include "core/events/MouseEvent.h"
-#include "core/dom/shadow/ShadowRoot.h"
+#include "core/events/TouchEvent.h"
+#include "core/frame/EventHandlerRegistry.h"
 #include "core/frame/LocalFrame.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/forms/StepRange.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "core/html/shadow/ShadowElementNames.h"
 #include "core/input/EventHandler.h"
 #include "core/layout/LayoutSliderContainer.h"
 #include "core/layout/LayoutSliderThumb.h"
 #include "core/layout/LayoutTheme.h"
 
@@ skipping 243 matching lines @@
         return mediaSliderThumbShadowPartId();
     default:
         return sliderThumbShadowPartId();
     }
 }
 
 // --------------------------------
 
 inline SliderContainerElement::SliderContainerElement(Document& document)
     : HTMLDivElement(document)
+    , m_hasTouchEventHandler(false)
 {
 }
 
 DEFINE_NODE_FACTORY(SliderContainerElement)
 
 LayoutObject* SliderContainerElement::createLayoutObject(const ComputedStyle&)
 {
     return new LayoutSliderContainer(this);
 }
 
+void SliderContainerElement::defaultEventHandler(Event* event)
+{
+    if (event->isTouchEvent()) {
+        handleTouchEvent(toTouchEvent(event));
+        return;
+    }
+}
+
+void SliderContainerElement::handleTouchEvent(TouchEvent* event)
+{
+    HTMLInputElement* input = toHTMLInputElement(shadowHost());
+    if (input->isDisabledOrReadOnly())
+        return;
+
+    if (event->type() == EventTypeNames::touchend) {
+        input->dispatchFormControlChangeEvent();
+        event->setDefaultHandled();
+        return;
+    }
+
+    TouchList* touches = event->targetTouches();
+    SliderThumbElement* thumb = toSliderThumbElement(input->userAgentShadowRoot()->getElementById(ShadowElementNames::sliderThumb()));
+    if (touches->length() == 1) {
+        thumb->setPositionFromPoint(touches->item(0)->absoluteLocation());
+    }
+}
+
 const AtomicString& SliderContainerElement::shadowPseudoId() const
 {
     DEFINE_STATIC_LOCAL(const AtomicString, mediaSliderContainer, ("-webkit-media-slider-container"));
     DEFINE_STATIC_LOCAL(const AtomicString, sliderContainer, ("-webkit-slider-container"));
 
     if (!shadowHost() || !shadowHost()->layoutObject())
         return sliderContainer;
 
     const ComputedStyle& sliderStyle = shadowHost()->layoutObject()->styleRef();
     switch (sliderStyle.appearance()) {
     case MediaSliderPart:
     case MediaSliderThumbPart:
     case MediaVolumeSliderPart:
     case MediaVolumeSliderThumbPart:
     case MediaFullScreenVolumeSliderPart:
     case MediaFullScreenVolumeSliderThumbPart:
         return mediaSliderContainer;
     default:
         return sliderContainer;
     }
 }
 
+void SliderContainerElement::updateTouchEventHandlerRegistry()
+{
+    if (m_hasTouchEventHandler) {
+        return;
+    }
+    if (document().frameHost() && document().lifecycle().state() < DocumentLifecycle::Stopping) {
+        EventHandlerRegistry& registry = document().frameHost()->eventHandlerRegistry();
+        registry.didAddEventHandler(*this, EventHandlerRegistry::TouchStartOrMoveEventPassive);
+        m_hasTouchEventHandler = true;
+    }
+}
+
+void SliderContainerElement::didMoveToNewDocument(Document& oldDocument)
+{
+    updateTouchEventHandlerRegistry();
+    HTMLElement::didMoveToNewDocument(oldDocument);
+}
+
+void SliderContainerElement::parserDidSetAttributes()

[tkent, 2016/08/17 01:32:00]

Why is it necessary though parseAttribute() calls updateTouchEventRegistry()?

+{
+    updateTouchEventHandlerRegistry();
+}
+
+void SliderContainerElement::parseAttribute(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& value)
+{
+    HTMLElement::parseAttribute(name, oldValue, value);
+    updateTouchEventHandlerRegistry();

[tkent, 2016/08/17 01:32:00]

Why do we need to call updateTouchEventHandlerRegistry() on attribute changes?

+}
+
+void SliderContainerElement::removeAllEventListeners()
+{
+    Node::removeAllEventListeners();
+    m_hasTouchEventHandler = false;
+}
+
 } // namespace blink