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

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

Index: third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp b/third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp
index 8d9d3f157686106527291c1d3c1f15c6a4c3c210..90b60a122fbfc7132034dad87eea6983b44198c3 100644
--- a/third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp
@@ -31,9 +31,11 @@
 
 #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"
@@ -297,6 +299,7 @@ const AtomicString& SliderThumbElement::shadowPseudoId() const
 
 inline SliderContainerElement::SliderContainerElement(Document& document)
     : HTMLDivElement(document)
+    , m_hasTouchEventHandler(false)
 {
 }
 
@@ -307,6 +310,33 @@ 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"));
@@ -329,4 +359,39 @@ const AtomicString& SliderContainerElement::shadowPseudoId() const
     }
 }
 
+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